documents plc opto 22 opto 22 pac control user guide

PAC CONTROL USER’S GUIDE

Form 1700-101124—November 2010

43044 Business Park Drive • Temecula • CA 92590-3614Phone: 800-321-OPTO (6786) or 951-695-3000

Fax: 800-832-OPTO (6786) or 951-695-2712www.opto22.com

Product Support Services800-TEK-OPTO (835-6786) or 951-695-3080

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Web: support.opto22.com

PAC Control User’s Guideii

PAC Control User’s GuideForm 1700-101124—November 2010

Copyright © 2010 Opto 22.All rights reserved.Printed in the United States of America.

The information in this manual has been checked carefully and is believed to be accurate; however, Opto 22 assumes no responsibility for possible inaccuracies or omissions. Specifications are subject to change without notice.

Opto 22 warrants all of its products to be free from defects in material or workmanship for 30 months from the manufacturing date code. This warranty is limited to the original cost of the unit only and does not cover installation, labor, or any other contingent costs. Opto 22 I/O modules and solid-state relays with date codes of 1/96 or later are guaranteed for life. This lifetime warranty excludes reed relay, SNAP serial communication modules, SNAP PID modules, and modules that contain mechanical contacts or switches. Opto 22 does not warrant any product, components, or parts not manufactured by Opto 22; for these items, the warranty from the original manufacturer applies. These products include, but are not limited to, OptoTerminal-G70, OptoTerminal-G75, and Sony Ericsson GT-48; see the product data sheet for specific warranty information. Refer to Opto 22 form number 1042 for complete warranty information.

Wired+Wireless controllers and brains and N-TRON wireless access points are licensed under one or more of the following patents: U.S. Patent No(s). 5282222, RE37802, 6963617; Canadian Patent No. 2064975; European Patent No. 1142245; French Patent No. 1142245; British Patent No. 1142245; Japanese Patent No. 2002535925A; German Patent No. 60011224.

Opto 22 FactoryFloor, Optomux, and Pamux are registered trademarks of Opto 22. Generation 4, ioControl, ioDisplay, ioManager, ioProject, ioUtilities, mistic, Nvio, Nvio.net Web Portal, OptoConnect, OptoControl, OptoDataLink, OptoDisplay, OptoOPCServer, OptoScript, OptoServer, OptoTerminal, OptoUtilities, PAC Control, PAC Display, PAC Manager, PAC Project, SNAP Ethernet I/O, SNAP I/O, SNAP OEM I/O, SNAP PAC System, SNAP Simple I/O, SNAP Ultimate I/O, and Wired+Wireless are trademarks of Opto 22.

ActiveX, JScript, Microsoft, MS-DOS, VBScript, Visual Basic, Visual C++, Windows, and Windows Vista are either registered trademarks or trademarks of Microsoft Corporation in the United States and other countries. Linux is a registered trademark of Linus Torvalds. Unicenter is a registered trademark of Computer Associates International, Inc. ARCNET is a registered trademark of Datapoint Corporation. Modbus is a registered trademark of Schneider Electric. Wiegand is a registered trademark of Sensor Engineering Corporation. Nokia, Nokia M2M Platform, Nokia M2M Gateway Software, and Nokia 31 GSM Connectivity Terminal are trademarks or registered trademarks of Nokia Corporation. Sony is a trademark of Sony Corporation. Ericsson is a trademark of Telefonaktiebolaget LM Ericsson. CompactLogix, MicroLogix, SLC, and RSLogix are trademarks of Rockwell Automation. Allen-Bradley and ControlLogix are a registered trademarks of Rockwell Automation. CIP and EtherNet/IP are trademarks of ODVA.

All other brand or product names are trademarks or registered trademarks of their respective companies or organizations.

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Table of Contents

Chapter 1: Welcome to PAC Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1About this Guide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Choosing Documentation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3Document Conventions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3Documents and Online Help . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4Product Support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5

Installing PAC Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5System Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6

Chapter 2: PAC Control Tutorial . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9In this Chapter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9

Opening the Strategy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10Saving the Strategy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11Examining the Strategy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

The Strategy Tree . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13Docking the Strategy Tree . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13Using Quick Find . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Opening a Chart . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15Opening a Block . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16Adding a Command . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20Configuring a Control Engine. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24Compiling the Strategy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27Running the Strategy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

Inspecting Messages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31Stepping Through the Chart . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31Auto Stepping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

Compiling and Downloading the Change. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

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Using a Watch Window . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39Closing the Strategy and Exiting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46What’s Next? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

Chapter 3: What Is PAC Control? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47In this Chapter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

About PAC Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47Control System Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

General Control Concepts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49Automation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49Control Engines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49Digital and Analog Inputs and Outputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49SNAP Special-Purpose I/O Modules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50

Key Features. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50PAC Control Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51PAC Control Main Window . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56

Status Bar . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57Toolbars . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58Strategy Tree . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60

Windows and Dialog Boxes in PAC Control. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61Using Tabs to View Open Windows . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61Docking Windows . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63Zooming in a Chart or Subroutine Window . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64Panning a Chart . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65Redrawing a Chart or Subroutine Window . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66Changing Column Width in a Dialog Box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67Sorting Data in a Dialog Box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67

Customizing PAC Control for Your Needs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69Setting Decimal, Binary, or Hex Display Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69Setting Up Applications to Launch from PAC Control . . . . . . . . . . . . . . . . . . . . . . . . . . 70

Keyboard and Mouse Shortcuts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71Online Help . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72

Chapter 4: Designing Your Strategy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73


Steps to Design. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73Solving the Problem . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74

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Building the Strategy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77Using and Improving the Strategy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81

Basic Rules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81Chart Guidelines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81Naming Conventions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82

Instruction Examples. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84Creating Messages to Display On Screen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84Error Handling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86Counting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86Using a Count Variable for Repetitive Actions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87Programming Case Statements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88Using a Timer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89Using a Flag Lock . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90Pointers and Indexing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92

Optimizing Throughput. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95

Chapter 5: Working with Control Engines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .97


Configuring Control Engines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97Defining a Control Engine on Your PC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98Associating the Control Engine with Your Strategy . . . . . . . . . . . . . . . . . . . . . . . . . . . 100

Using Network Segmenting in PAC Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101Using Ethernet Link Redundancy in PAC Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102

System Architecture for Ethernet Link Redundancy . . . . . . . . . . . . . . . . . . . . . . . . . . . 103Configuring Ethernet Link Redundancy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106Using Strategies with Link Redundancy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107

Using Redundant Controllers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107Changing or Deleting a Control Engine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107

Changing a Control Engine’s Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108Changing the Control Engine that Receives the Downloaded Strategy . . . . . . . . 108Removing a Control Engine’s Association with a Strategy . . . . . . . . . . . . . . . . . . . . . 109Deleting a Control Engine from Your PC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109

Inspecting Control Engines and the Queue. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109Inspecting Control Engines in Debug Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109Viewing the Message Queue . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111Inspecting Control Engines from the PAC Terminal Utility . . . . . . . . . . . . . . . . . . . . . 114

Downloading Files to the Control Engine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114Archiving Strategies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115Downloading Files Without Opening PAC Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118

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Chapter 6: Working with I/O . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119

Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119In this Chapter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119

Choosing a Configuration Tool . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119Importing I/O Configuration into PAC Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121Copying I/O Configurations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121

Adding an I/O Unit. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122Changing the Baud Rate for Serial I/O Units . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125Changing the Baud Rate and Mode for Serial I/O Units . . . . . . . . . . . . . . . . . . . . . . . . 126Tuning the I/O Unit Timeout Value for Ethernet I/O Units . . . . . . . . . . . . . . . . . . . . . 127Changing Configured I/O Units . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 128Deleting Configured I/O Units . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 128

Adding I/O Points. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 128Adding a Digital I/O Point . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 128Adding an Analog I/O Point . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132

Configuring a Serial Module . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 137Changing Point Configuration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 137

Moving a Configured I/O Point . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 137Copying a Configured I/O Point . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138Changing a Configured I/O Point . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141Deleting a Configured I/O Point . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141

Configuring PID Loops . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141PIDs and Strategies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 142Adding a PID Loop . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 142Changing a PID Loop . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147Deleting a PID Loop . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147

Inspecting I/O in Debug Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 148Inspecting I/O Units and Saving Settings to Flash . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 148Inspecting Digital I/O Points . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 149Inspecting Analog I/O Points . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151

Inspecting and Tuning PID Loops . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153Inspecting a PID . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153Determining System Lag . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 154Tuning a PID Loop . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 159

Using Watch Windows for Monitoring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 165Creating a Watch Window . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 165Opening an Existing Watch Window . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 166Working in Watch Windows . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 167

Chapter 7: Working with Strategies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 169

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Creating a New Strategy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 169Opening a Strategy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 170

Opening an Existing Strategy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 170Opening an ioControl Strategy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 170Opening a Recently Used Strategy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 170Loading a Strategy or Mode at Startup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 171Opening Strategies in PAC Control Basic and PAC Control Professional . . . . . . . . 171Opening an OptoControl Strategy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 171

Saving and Closing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 171Saving the Strategy and All Charts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 171Saving the Strategy and Some Charts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 171Saving the Strategy to a New Name . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 172Saving Before Debugging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 172Closing a Strategy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 173

Saving a Strategy to Flash . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 173Saving to Flash Once . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 173Saving to Flash on Every Download . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 173

Archiving Strategies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 174Archiving to the Computer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 174Archiving to the Control Engine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 175

Compiling and Downloading. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 175Compiling and Downloading in One Step . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 176Switching the Strategy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 178Compiling without Downloading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 178Downloading Only . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 179Background Downloading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 179Downloading Without Using PAC Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 181Changing Download Compression . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183

Running a Strategy Manually . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 184Running a Strategy Automatically (Autorun) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 184

Protecting a Running Strategy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 185Stopping a Strategy. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 185Debugging. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 185

Choosing Debug Level . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 185Changing Debugger Speed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 186Pausing a Chart or Subroutine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 187Stepping Through a Chart or Subroutine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 187Setting and Removing Breakpoints . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 190Managing Multiple Breakpoints . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 191

PAC Control User’s Guideviii

Interpreting Elapsed Times . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 192Viewing and Printing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 192

Viewing Strategy Filename and Path . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 193Viewing an Individual Chart or Subroutine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 193Viewing All Charts in a Strategy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 193Printing Chart or Subroutine Graphics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 194Viewing and Printing Strategy or Subroutine Commands . . . . . . . . . . . . . . . . . . . . . 197Viewing and Printing Strategy or Subroutine Elements . . . . . . . . . . . . . . . . . . . . . . . 198Viewing and Printing a Cross Reference . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 200Viewing and Printing a Bill of Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 201Viewing and Printing I/O Point Mappings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 201

Searching and Replacing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 203Searching . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 203Replacing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 205

Legacy Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 207Existing Strategies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 207New Strategies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 207Enabling Legacy Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 208

Chapter 8: Working with Flowcharts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 211


Creating a New Chart . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 211Working with Chart Elements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 213

Chart Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 213Changing the Appearance of Elements in a Chart Window . . . . . . . . . . . . . . . . . . . 214Drawing Blocks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 216Naming Blocks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 217Connecting Blocks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 218Adding Text . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 220Selecting Elements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 221Moving Elements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 222Cutting, Copying, and Pasting Elements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 222Deleting Elements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 223Changing Element Color and Size . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 223

Opening, Saving, and Closing Charts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 224Opening a Chart . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 224Saving a Chart . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 224Closing a Chart . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 224

Copying, Renaming, and Deleting Charts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 225Copying a Chart . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 225

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Renaming a Chart . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 225Deleting a Chart . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 226

Printing Charts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 226Exporting and Importing Charts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 227

Exporting a Chart . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 227Importing a Chart . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 228

Chapter 9: Using Variables and Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . 229


About Variables. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 229Types of Data in a Variable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 230Variables in PAC Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 231Persistent Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 233Literals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 233

Adding Variables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 233Adding Tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 237

Adding Table Variables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 237Setting Initial Values in Variables and Tables During Strategy Download . . . . . . . . . . . 238Changing a Configured Variable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 241Deleting a Variable. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 242Viewing Variables in Debug Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 242

Viewing Numeric, String, and Communication Handle Variables . . . . . . . . . . . . . . 242Viewing Pointer Variables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 244Viewing Numeric and String Tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 245Viewing Pointer Tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 247

Adding Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 247Changing a Command. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 251Deleting a Command . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 251

Permanently Deleting a Command . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 251Commenting Out a Command . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 252

Cutting or Copying a Command. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 252Pasting a Command . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 253Configuring a Continue Block . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 253Viewing and Printing Chart Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 254

Chapter 10: Programming with Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . 255


PAC Control User’s Guidex

Analog Point Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 256Offset and Gain Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 256Minimum/Maximum Values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 257Analog Points and OptoScript Code . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 257

Chart Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 258About the Task Queue . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 258

Communication Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 259Communication Handles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 259Using TCP Communication Handles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 261Using the Control Engine’s File System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 269Moving Files via FTP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 275Using Serial Communication Handles to Communicate with Serial Devices . . . . 278

Control Engine Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 282Commands Relating to Permanent Storage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 282

Digital Point Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 283States, Latches, and Counters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 283Totalizers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 285Pulses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 285IVAL and XVAL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 286Additional Commands to Use with Standard Digital Points . . . . . . . . . . . . . . . . . . . 287Standard Digital Points and OptoScript Code . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 287

Error Handling Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 288IO Enabler Sample Strategies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 288

I/O Unit Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 289Commands for Ethernet Link Redundancy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 289Table Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 290

I/O Unit—Event Message Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 291I/O Unit—Memory Map Commands. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 292I/O Unit—Scratch Pad Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 293Logical Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 295

Understanding Logical Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 295Mathematical Commands. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 297

Using Integers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 297Using Floats . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 297Mixing and Converting Integers and Floats . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 300

Miscellaneous Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 301Comment Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 301

PID—Ethernet Commands. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 302What is a PID? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 302PID Loops on I/O Units . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 303Algorithm Choices (PID) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 303

PAC Control User’s Guide xixi

Pointer Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 306Understanding Pointers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 306Advantages of Using Pointers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 307Referencing Objects with Pointers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 307

Simulation Commands. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 308String Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 309

Using Strings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 309String Length and Width . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 310Using Numeric Tables as an Alternative to Strings . . . . . . . . . . . . . . . . . . . . . . . . . . . . 310Strings and Multitasking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 310Adding Control Characters to a String . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 311Sample String Variable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 311Sample String Table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 312String Data Extraction Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 312String Building Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 313Comparison to Visual Basic and C . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 315Convert-to-String Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 316ASCII Table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 317

Time/Date Commands. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 318Timing Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 319

Delay Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 319Using Timers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 319

Chapter 11: Using OptoScript . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 321


About OptoScript. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 322When To Use OptoScript . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 322

For Math Expressions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 323For String Handling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 325For Complex Loops . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 327For Case Statements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 328For Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 329For Combining Expressions, Operators, and Conditions . . . . . . . . . . . . . . . . . . . . . . . 330

OptoScript Functions and Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 331Standard and OptoScript Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 331Using I/O in OptoScript . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 331

OptoScript Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 332More About Syntax with Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 333

OptoScript Data Types and Variables. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 334Variable Name Conventions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 334

PAC Control User’s Guidexii

Using Numeric Literals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 335Making Assignments to Numeric Variables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 335Using Strings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 335Working with Pointers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 337Working with Tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 338

OptoScript Expressions and Operators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 338Using Mathematical Expressions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 339Using Comparison Operators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 339Using Logical Operators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 341Using Bitwise Operators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 341Precedence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 342

OptoScript Control Structures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 342If Statements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 343Switch or Case Statements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 343While Loops . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 344Repeat Loops . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 345For Loops . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 345

Using the OptoScript Editor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 346Troubleshooting “Unable To Find” Errors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 350Troubleshooting Syntax Errors. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 351Debugging Strategies with OptoScript. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 352

Chapter 12: Using Subroutines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 353


About Subroutines. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 353Data Types for Subroutines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 354

Creating Subroutines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 355Tips for Subroutines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 355Drawing the Flowchart . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 355Configuring Subroutine Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 357Adding Commands and Local Variables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 360Compiling and Saving the Subroutine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 361

Using Subroutines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 361Including a Subroutine in a Strategy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 361Adding a Subroutine Instruction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 362Debugging Subroutines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 364

Viewing Subroutines. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 364Viewing All Subroutines in a Strategy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 365

Printing Subroutines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 365

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Appendix A: Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 367

How to Begin Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3671. Read Any Error Message Box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3672. Check Communication with the Control Engine . . . . . . . . . . . . . . . . . . . . . . . . . . . 3683. Check the Message Queue . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3684. Check Status Codes in Your Strategy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3685. Call Product Support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 368

Strategy Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 368If You Cannot Delete an Item . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 368If You Have Memory Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 369

Checking Communication with the Control Engine. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 370Resolving Communication Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 371

Matching PAC Control Configuration to the Real World . . . . . . . . . . . . . . . . . . . . . . . 371Resolving TCP/IP Cannot Connect Errors (-412) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 372

Other Troubleshooting Tools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 373Checking Detailed Communication Information Using PAC Message Viewer . . . 373Checking File Versions for Opto 22 Software . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 375Problems with Permissions in Windows . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 376

Appendix B: Errors and Messages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 379

Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 379Types of Errors. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 379

PAC Control Errors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 380Queue Messages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 380Status Codes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 381Naming Conflicts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 381

List of Common Messages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 382

Appendix C: PAC Control Files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 389

Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 389Files Related to a Strategy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 390Files Associated with a Subroutine. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 390Files in the PAC Control Directory. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 391

Appendix D: Sample Strategy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 393

Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 393Factory Schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 393Description of the Process. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 394

Dough Vessel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 394

PAC Control User’s Guidexiv

Chip Hopper . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 394Oven . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 394Inspection Station . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 394Conveyor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 394Emergency Stops . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 395

Required I/O. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 395Analog I/O . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 395Digital I/O . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 395

Appendix E: OptoScript Language Reference . . . . . . . . . . . . . . . . . . . . . . . . . . 397

Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 397OptoScript Comparison with Standard Programming Languages . . . . . . . . . . . . . . . . . 397

Function Comparison . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 398Variable Comparison . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 402

Notes to Experienced Programmers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 402Variable Database and Other Surprises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 402PAC Control's Target Audience . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 402Language Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 403

OptoScript Lexical Reference . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 404Token Syntax Legend . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 404Literals and Names . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 405Keywords (Reserved Words) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 406Operators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 406Comments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 407

OptoScript Grammar Syntax Reference . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 407

Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 413

PAC Control User’s Guide 11

1: Welcome to PAC ControlChapter 1

1: Welcome to PAC Control

IntroductionWelcome to PAC Control™, Opto 22’s visual control language for Opto 22 SNAP PAC control systems and the input/output (I/O) units that work with them.

PAC Control makes it easy to write control applications with little or no programming experience. If you know how to design a control application and can draw some flowcharts to describe it, you already know the basics of PAC Control. At the same time, PAC Control provides a complete and powerful set of commands, as well as the OptoScript™ programming language, to meet your most demanding industrial control needs.

PAC Control comes in two forms: PAC Control Basic and PAC Control Professional™.

• PAC Control Basic is included in the purchase of an Opto 22 SNAP PAC controller and is also available as a free download from our website, www.opto22.com. PAC Control Basic includes both flowchart and OptoScript programming, subroutines, a graphical debugger, and about 400 commands.

• PAC Control Professional is available for purchase either separately or as part of the complete PAC Project Professional™ software suite. The Professional version of PAC Control adds Ethernet link to controllers and I/O units, controller-level redundancy, supports additional features in SNAP PAC I/O units (such as ramping and pulsing), and offers additional data types in subroutines. PAC Control Professional also provides a migration path for Opto 22 FactoryFloor™ customers by adding support for serial-based mistic® I/O units and by including a conversion utility to help customers move older OptoControl™ strategies to PAC Control. PAC Control Professional includes about 500 commands. For information on features supported by a specific controller, see the controller documentation.

About this GuideThis user’s guide not only teaches you how to use PAC Control, but also provides programming instruction and tips. The separate PAC Control Command Reference describes in detail all PAC Control programming commands and instructions.

ABOUT THIS GUIDE

PAC Control User’s Guide2

This guide assumes that you are already familiar with Microsoft® Windows® on your personal computer, including how to use a mouse, standard commands, and menu items to open, save, and close files. If you are not familiar with Windows or your PC, refer to the documentation from Microsoft and your computer manufacturer.

This guide covers both PAC Control Basic and PAC Control Professional. Features that are available only in PAC Control Professional are marked with .

The Basic icon indicates features or functions that apply only to PAC Control Basic.

The Professional icon indicates features or functions that apply only to PAC Control Professional.

Here’s what is in this user’s guide:

1: Welcome to PAC Control—Information about the guide and how to reach Opto 22 Product Support.

2: PAC Control Tutorial—A tutorial designed to help you use PAC Control as quickly as possible. The chapter leads you through a sample strategy that you can manipulate, download, and run in Debug mode.

3: What Is PAC Control?—An introduction to PAC Control, key terminology, and the main windows and toolbars.

4: Designing Your Strategy—Programming in PAC Control: how to get from your real-world control problem to a working strategy.

5: Working with Control Engines—How to configure and communicate with control engines.

6: Working with I/O—How to configure and communicate with input/output (I/O) units, I/O points, and PID loops.

7: Working with Strategies—Detailed steps for creating, compiling, and running strategies.

8: Working with Flowcharts—Detailed steps for creating and working with the flowcharts that make up your strategy.

9: Using Variables and Commands—Steps for configuring the seven types of variables you can use in programming: communication handle, numeric, string, pointer, numeric table, string table, and pointer table variables. Also shows how to use the commands that control the I/O and variables you’ve configured.

10: Programming with Commands—Important tips on using PAC Control commands to accomplish what you want in your strategy.

11: Using OptoScript—Details on the optional scripting language available in PAC Control for complex loops, string handling, and mathematical expressions.

12: Using Subroutines—How to use subroutines to streamline your strategy development.

A: Troubleshooting—Tips for resolving communication problems and other difficulties you may encounter.

CHAPTER 1: WELCOME TO PAC CONTROL


B: Errors and Messages—Types of errors, where you’ll see them, and the causes of common errors.

C: PAC Control Files—A list of all PAC Control files located in the PAC Control directory and in any strategy directory.

D: Sample Strategy—An illustration and description of the sample “Cookies” strategy used in Chapter 1.

E: OptoScript Language Reference—Details about OptoScript code, including comparisons to other languages, lexical reference, and notes to experienced programmers.

Index—Alphabetical list of key words and the pages where they are located.

Choosing DocumentationThis user’s guide contains the latest information you need to use PAC Control with your SNAP PAC system. However, if you are using Opto 22 “legacy” products designed to work with pre-SNAP PAC systems, see form 1710, PAC Control User’s Guide, Legacy Edition. The legacy version includes references to pre-SNAP PAC devices and commands, which are not included in this guide.

form 1For information on what we mean by “legacy” and how to migrate from an older system to a SNAP PAC system, see form 1688, SNAP PAC System Migration Technical Note. For information on how to enable legacy functionality in PAC Control for a specific strategy, see “Legacy Options” on page 207.

Document ConventionsThe following conventions are used in this document:

• The Pro icon next to text indicates that a feature is available only in PAC Control Professional, not in PAC Control Basic.

• Italic typeface indicates emphasis and is used for book titles. (Example: “See the PAC Display User’s Guide for details.”)

• Names of menus, commands, dialog boxes, fields, and buttons are capitalized as they appear in the product. (Example: “From the File menu, select Print.”)

• File names appear either in all capital letters or in mixed case, depending on the file name itself. (Example: “Open the file TEST1.txt.”)

• Key names appear in small capital letters. (Example: “Press SHIFT.”)

• Key press combinations are indicated by plus signs between two or more key names. For example, SHIFT+F1 is the result of holding down the shift key, then pressing and releasing the F1 key. Similarly, CTRL+ALT+DELETE is the result of pressing and holding the CTRL and ALT keys, then pressing and releasing the DELETE key.

• “Click” means press and release the left mouse button on the referenced item. “Right-click” means press and release the right mouse button on the item.

ABOUT THIS GUIDE


• Menu commands are referred to with the Menu > Command convention. For example, “File > Open Project” means to select the Open Project command from the File menu.

• Numbered lists indicate procedures to be followed sequentially. Bulleted lists (such as this one) provide general information.

Documents and Online HelpTo help you understand and use PAC Control systems, the following resources are provided:

• Online Help is available in PAC Control and in most of the utility applications. To open online Help, choose Help > Contents and Index in any screen.

• PAC Control User’s Guide shows how to install and use PAC Control.

• PAC Control Command Reference contains detailed information about each command (instruction) available in PAC Control.

• A quick reference card, located in the front pocket of the PAC Control Command Reference, lists all PAC Control commands plus their OptoScript™ code equivalents and arguments.

• PAC Manager User’s Guide and other guides provided with specific hardware help you install, configure, and use controllers and I/O units.

Online versions (Adobe® Acrobat® format) of PAC Control documents are provided on the CD that came with your controller or purchase of Professional software and are also available from the Help menu in PAC Control. To view a document, select Help > Manuals, and then choose a document from the submenu.

When you purchase PAC Control Professional or PAC Project Professional, you also receive a complete set of printed documents.

Resources are also available on the Opto 22 Web site at www.opto22.com. You can conveniently access the Web site using the Help menu in PAC Control. Select Help > Opto 22 on the Web, and then select an online resource from the submenu.



Product SupportIf you have any questions about PAC Control, you can call, fax, or email Opto 22 Product Support.

Phone: 800-TEK-OPTO (835-6786)951-695-3080(Hours are Monday through Friday, 7 a.m. to 5 p.m. Pacific Time)

Fax: 951-695-3017

Email: [email protected]

Opto 22 website: www.opto22.com

When calling for technical support, be prepared to provide the following information about your system to the Product Support engineer:

• Software and version being used

• Firmware versions

• PC configuration (type of processor, speed, memory, and operating system)

• A complete description of your hardware and operating systems, including:

– type of power supply

– types of I/O units installed

– third-party devices installed (for example, barcode readers)

• Specific error messages seen.

Installing PAC ControlPAC Control installation is easy and quick. Insert the CD containing PAC Control in your CD-ROM drive, and the installation wizard should appear. If the wizard does not appear, start Windows Explorer and navigate to your CD-ROM drive. Double-click Setup.exe to begin installation.

NOTE: If you run PAC Project applications in Microsoft Windows XP, make sure to use the Windows Classic theme. Otherwise, a Microsoft bug with how themes are handled may cause the system to crash.

If you have trouble installing PAC Control, contact Opto 22 Product Support at 800-835-6786 or 951-695-3080.

NOTE: Email messages and phone calls to Opto 22 Product Support are grouped together and answered in the order received.

INSTALLING PAC CONTROL


System Requirements

Installation Requirements

Here’s what you need to install and run PAC Control. If you are using PAC Display, please note its requirements in the PAC Display User’s Guide.

• A computer with at least the minimum processor and memory required for your version of Microsoft Windows, and Ethernet capability. Additional memory may be required for some configurations.

• VGA or higher resolution monitor (Super VGA recommended). Minimum size: 800x600 with small fonts.

• Mouse or other pointing device

• Installed Windows printer (optional)

• Microsoft Windows 7 Professional (32-bit or 64-bit), Windows Vista® Business (32-bit), or Windows XP Professional (32-bit, with Service Pack 2 or higher)

NOTE: Microsoft Windows server and embedded Windows operating systems are not supported.

• For available hard disk requirements, please see the PAC Project Release Notes

• Compatible control engine and I/O unit(s), as shown in the following section.

Compatible Control Engines and I/O Units

The following control engine and I/O unit combinations are compatible with PAC Control Basic and PAC Control Professional as shown:

Important Note on Disk Drives

Opto 22 applications, including PAC Control, perform best when using files from a local hard disk. Network drives may be used, but performance may suffer and depends upon the

Using this control engine PAC Control Basic supports these I/O units PAC Control Pro supports these I/O units

SNAP PAC S-series controller

SNAP-PAC-R1SNAP-PAC-R1-W*SNAP-PAC-R2SNAP-PAC-R2-W*SNAP-PAC-EB1SNAP-PAC-EB1-W*SNAP-PAC-EB2SNAP-PAC-EB2-W*SNAP-PAC-SB1SNAP-PAC-SB2

SNAP-PAC-R1SNAP-PAC-R1-W*SNAP-PAC-R2SNAP-PAC-R2-W*SNAP-PAC-EB1SNAP-PAC-EB1-W*SNAP-PAC-EB2SNAP-PAC-EB2-W*SNAP-PAC-SB1SNAP-PAC-SB2

SNAP PAC R-series controller

SNAP-PAC-R1SNAP-PAC-R2SNAP-PAC-EB1SNAP-PAC-EB2

SNAP-PAC-R1SNAP-PAC-R2SNAP-PAC-EB1SNAP-PAC-EB2

* Wired+Wireless PACs and I/O can be used on a wired Ethernet network or on a wireless LAN.



speed and reliability of the network. While it may be possible to use other drive types, such as floppy disks, key chain USB drives, and memory cards, their use is not recommended. They are better suited for transferring files rather than directly accessing them.

INSTALLING PAC CONTROL



2: 2: PAC Control TutorialChapter 2

2: PAC Control Tutorial

IntroductionIn this chapter, we’ll start with a sample strategy: a control application for a simple cookie factory. You’ll learn how to work with strategies, open and manipulate flowcharts, work with variables and I/O points, configure a control engine, compile and download a strategy, run it in Debug mode, make an online change, and more. The tutorial can be used with either PAC Control Basic or PAC Control Professional. (PAC Control Basic is shown in the graphics.)

The best way to use the tutorial is to sit down at your computer and follow it through. To start, all you need is PAC Control, which allows you to do everything up to the point of downloading your strategy. To do the complete tutorial you will need the controller and I/O included in a SNAP PAC Learning Center. For more information, go to the Opto 22 website, www.Opto22.com and search on the part number, SNAP-PACLC.

In this ChapterOpening the Strategy ................................................10Saving the Strategy.....................................................11Examining the Strategy.............................................12Opening a Chart...........................................................15Opening a Block...........................................................16Adding a Command...................................................20Configuring a Control Engine ................................24Compiling the Strategy.............................................27Running the Strategy.................................................29Compiling and Downloading the Change.......37Using a Watch Window ............................................39Closing the Strategy and Exiting ..........................46What’s Next? ..................................................................46

OPENING THE STRATEGY


Opening the StrategyA strategy is a complete control program developed in PAC Control. Our sample strategy controls a cookie factory. The sample strategy is described in detail on page 393, but for now, let’s just open and explore it.1. Start PAC Control by clicking the Start button and selecting Programs > Opto 22 > PAC

Project 9.0 > PAC Control.

The PAC Control main window opens.

2. Click the Open Strategy button on the toolbar, or choose File > Open Strategy.3. In the Open Strategy dialog box, navigate to PAC Project 9.0\Control Pro (or Basic)

Examples.4. In the Examples directory, double-click the ioCookies subdirectory to open it.

The strategy file Cookies.idb appears.

CHAPTER 2: PAC CONTROL TUTORIAL


5. Double-click the Cookies.idb file to open it.

NOTE: If a File Format Change dialog opens warning that you are about to open strategy saved using an earlier version of PAC Control, you can safely ignore the message and click Yes.

The Cookies strategy opens and the PAC Control window now shows the Cookies strategy (yours may look somewhat different).

Saving the StrategyNow let’s save the strategy to a new name, so we can change it while leaving the original intact.1. Select File > Save Strategy As.

Since each PAC Control strategy must be located in its own directory, you cannot save the strategy to a new name in its current location.

EXAMINING THE STRATEGY


2. Click the Up One Level button to move up to the Examples directory.

3. Click the Create New Folder button .

The new folder appears in the list.

4. Type My Cookies to replace New Folder. Double-click the folder to open it. 5. Click in the File name field and type Cookies.

The dialog box now looks like this:

6. Click Save.

The strategy is saved as Cookies in the My Cookies directory.

Examining the StrategyBriefly, our cookie factory includes a tank of pre-mixed cookie dough, a tank of chocolate chips, an oven, a visual inspection station, a conveyor belt, and some compressed air to blow rejected cookies off the belt. The process starts when a ball of dough drops on the belt. It moves along under the chip tank to receive some chips, and then it moves into the oven to be baked. The next stop is an inspection, where rejected cookies are blown off the belt and good cookies move along to shipping. Should anything go wrong, we also have some alarms built in to stop the process when necessary.

The best way to see all the components of the strategy is to look at the Strategy Tree.



The Strategy TreeAs with any window in PAC Control, you can move the Strategy Tree window by clicking and dragging the title bar, you can minimize, maximize, or dock it by clicking buttons at the right of the title bar, or you can reshape it by dragging any edge in any direction.

However, the Strategy Tree window is unique in that it must remain open, since closing it is equivalent to closing the strategy.

The Strategy Tree works like Windows Explorer: you can expand and collapse folders to show or hide what is in them.

A quick look at the tree reveals that our strategy includes five flowcharts (in the Charts folder), eight Numeric Variables, and one Mixed I/O Unit (with both analog and digital points). The Strategy Tree not only shows you all components of the strategy but also provides shortcuts to many common PAC Control activities, for example, opening flowcharts.

Docking the Strategy TreeSince the Strategy Tree is so useful, you’ll probably want to keep it visible while you create and debug your strategy. To keep the Strategy Tree window always visible, you can dock it in a separate frame. 1. Click the docking icon in the upper-right corner of the Strategy Tree window.

The Strategy Tree moves into its own frame at the left side of the main window.

Expanded Charts folder

EXAMINING THE STRATEGY


2. To change the width of the Strategy Tree’s frame, move your mouse over the right side of the frame. When the cursor changes, click and drag the side to make the frame wider or narrower.

Using Quick FindThe quick-find tool at the bottom of the strategy tree enables you to find items quickly in the tree. Use the Next and Prev buttons (or F3 and SHIFT+F3) to find multiple matches. Any partial match will work.

For example, if you enter the word, “setpoint,” when you click Next, the first match is found.

Docked Strategy Tree

Quick find tool



When you click Next again, the next match is found.

Opening a ChartEvery control process can be planned and mapped out using one or several PAC Control flowcharts, or charts. Because flowcharts are easy to follow, PAC Control strategies are easy to understand. For an example, let’s take a look at the Dough_Chip_Control chart. 1. With the Charts folder expanded, double-click the Dough_Chip_Control chart name

on the Strategy Tree. (You can also open a chart by selecting Chart > Open and navigating to the chart name.)

The chart appears somewhere in the large frame of the main window.

Match

Maximize button

OPENING A BLOCK


2. Click and drag the title bar of the chart window if necessary to see the maximize button at the upper right. Click the maximize button.

The chart now covers the whole frame. Notice the tabs at the bottom of the main window; the white tab tells you you’re viewing a chart, and the gray tab shows the chart’s name.

Let’s take a closer look at what this chart does. Even without its descriptive comments, it’s easy to see that this program segment begins by starting a conveyor belt. If the belt is not running at the correct speed, the process goes into a loop until the speed is correct. When it is correct, dough is dropped on the belt, and then chips are dropped on the dough. The process then loops back to re-evaluate the conveyor speed, waiting if it’s incorrect, and dropping more dough and chips if it’s correct.

The rectangular-shaped blocks are called action blocks. They do things. The diamond-shaped blocks are condition blocks. They decide things. Charts may also contain other blocks, including oval-shaped continue blocks, which route the program logic back to another block in the same chart, and hexagon-shaped script blocks, which contain instructions and logic written in PAC Control’s built-in OptoScript programming language.

Connections link the blocks together and show how the program logic flows. Action blocks exit through just one connection, since they always go in one direction. Condition blocks exit through two connections, one for a true evaluation and the other for a false evaluation.

Opening a BlockLet’s see what’s in a block.

Gray tab shows chart name.

White tab shows this is a chart.



1. Double-click the Drop Dough block.

The Instructions dialog box appears.

This block contains four instructions: Move, Turn On, Delay (Sec), and Turn Off. Each one has a description above it.

2. Double-click the Turn On instruction to see more about it. (You could also click it once and click Modify).

The Edit Instruction dialog box for the Turn On command appears.

Here we see the details of the command, which simply turns on the digital output Dough_Dispense_Valve. In other words, it opens the valve.

3. Close the Edit Instruction dialog box by clicking OK or Cancel.4. Back in the Drop Dough block’s Instructions dialog box, move your cursor to the

bottom right edge of the dialog box.

When your cursor changes to a bidirectional arrow, you can resize this dialog box by clicking and dragging any edge.

5. Close the Instructions - Dough_Chip_Control - Drop Dough dialog box by clicking Close or by pressing ESC.

OPENING A BLOCK


Before we leave the Dough_Chip_Control chart, let’s make a cosmetic change. We noted earlier that we didn’t have any continue blocks in this chart. Let’s add one to replace the long connection that loops from the Drop Chips block up to the Speed OK? block.

6. Select the connection line by clicking it at a bend or junction point, and delete it by pressing DELETE. Click the down arrow at the bottom right of the chart window once to scroll down a little.

7. Now click the continue block tool in the toolbar.

When you bring the mouse back into the chart area, an oval outline appears, representing the new continue block.

8. Position the oval about half an inch below the Drop Chips block, and click your mouse button once.

A continue block appears with the default name Block 19. (The number on yours may be different.) If you move the mouse again, a new oval outline follows. Deactivate the continue block tool by clicking the right mouse button or by pressing ESC.

Your screen should now look like this:

9. Connect the Drop Chips block to this new block by clicking the connection tool in the toolbar. Click once in the block the connection is coming from, Drop Chips.

If you move your cursor around the screen, you see a connection following your movements. If you move the cursor to the top of Block 19, the connection becomes a short line from the bottom center of Drop Chips to the top center of Block 19.

10. Click inside the upper part of Block 19 to complete the connection. Click the right mouse button or press ESC to release the tool, returning your cursor to an arrow.

Let’s name Block 19 something more descriptive.



11. Click Block 19 once to select it, then right-click it and select Name from its pop-up menu.

The Name Block dialog box appears.

12. Type Back to ‘Speed OK?’ right over the selected text, then click OK.

The chart now looks like this:

Now let’s give the continue block its instructions.

13. Double-click the continue block to see a list of all the blocks in the chart.

14. Select the Speed OK? block by clicking it once, and then click OK.

ADDING A COMMAND


When the program reaches the continue block, it returns to the Speed OK? block. We haven’t changed the way the program works; we’ve just done the same thing in a different way. Continue blocks are useful in a complex chart to avoid crossing connection lines.

Adding a CommandNow we’re going to add a command, or instruction, to a block in the Dough_Chip_Control chart. We’ll add the command so we can keep track of the number of cookies we produce.1. Double-click the Drop Dough block.

We’ll add the new instruction (command) between the Turn On and Delay (Sec) commands.

2. Click anywhere on Delay (Sec) to highlight this command.

This highlight indicates the position where the next command is added.

3. Click Add to open the Add Instruction dialog box.



If you knew the exact name of the command to enter, you could type it over Absolute Value (which is first in the alphabetical list of commands). As you typed, the first command that matched the pattern you entered would be filled in automatically. For example, if you really wanted to enter Absolute Value, you would start typing abs.

Another way to add a command is to click the down arrow just to the left of the Select button. You could scroll through the resulting list of commands to find the right one.

The third way to enter a command is the one we’ll use here.

4. Click Select.

All PAC Control command groups are listed on the left, and commands in the highlighted group are listed on the right. The command we want has something to do with increasing a counter. Counting sounds like math, so let’s try the Mathematical group.

5. Click Mathematical on the left to highlight it, then scroll down the list on the right until you find the command Increment Variable. Click it once.

Notice that if you need information about any command, you can click the Command Help button.

ADDING A COMMAND


6. Click OK and this command is entered in the Add Instruction dialog box.

The cursor is automatically moved to the next field, which is Comment. Comments are optional; they can help someone else understand the purpose of the instruction.

7. In the Comment field, type Increment a counter of cookies produced.8. Next, click the arrow in the Type field, the one that currently reads All Valid Types.

This list shows what those valid types are: a float variable, an integer 32 variable, and an integer 64 variable.

9. Counters are integers, so select Integer 32 Variable.

Now we’re going to add the integer 32 variable to increment, which will be called nCookie_Counter.

10. Click the arrow in the Name field, which currently reads bStartFlag.

The drop-down list shows all variables currently configured as integer 32 variables:

nCookie_Counter is not in the list, because we never needed it before, so we never created it. We’ll create it now using what we call on-the-fly configuration.

11. Highlight bStartFlag and type the new variable name, nCookie_Counter, right over it.

As soon as you try to do something else, such as click OK to close the dialog box, the following message appears.

12. Click Yes.



Notice that the name (nCookie_Counter) and type (Integer 32) have already been filled in.

13. Add a description, if you wish. Leave the initial value at zero, which is the default. Then click OK to accept the data and close the dialog box.

14. In the Add Instruction dialog box, click OK.

The new instruction appears in the Instructions window for Drop Dough.

But maybe it makes more sense to start the counter at the beginning of the process, rather than in the middle, after some dough has already been dropped.

15. With the Increment Variable command highlighted, press the right mouse button and select Cut from the pop-up menu.

You can also use CTRL+X to cut. Cutting puts the instruction in the Windows Clipboard.

16. Now click Turn On to highlight it. Click the right mouse button and select Paste from the pop-up menu.

You can also use CTRL+V to paste. The Increment Variable command is pasted above the highlighted instruction, like this:

CONFIGURING A CONTROL ENGINE


17. Click Close to return to the chart.

You’ve just added a cookie counter. On the Strategy Tree, open the Numeric Variables folder in the Variables folder. The new numeric variable is there.

18. Save the changes you’ve made by clicking the Save Strategy button on the toolbar. Click OK to save.

Now we’re ready to download the strategy to a control engine. But first we have to tell PAC Control that we have a control engine.

Configuring a Control EngineUp to this point, we’ve been able to play around in PAC Control without hardware. Now it’s time to configure a control engine.1. If you have a PAC Control-compatible control engine and I/O unit you can use, make

sure they are on the same network as your PC, and make sure you have loaded the most recent firmware.

For a list of compatible control engines and I/O units, see page 6. For instructions to load firmware, see Opto 22 form 1704, the PAC Manager User’s Guide.

2. Turn the I/O unit off and then back on again.3. Double-click the Control Engines folder on the Strategy Tree, or select Configure >

Control Engines.

The Configure Control Engines dialog box appears.



Since we haven’t configured a control engine yet, there are no control engines in the list.

4. Click Add.

5. Click Add again to add a control engine.

The Control Engine Configuration dialog box appears.

CONFIGURING A CONTROL ENGINE


6. Enter Cookie Controller as the control engine name.

The name can contain letters, numbers, spaces, and most other characters except colons and square brackets. Spaces cannot be used as first or last characters.

7. Under System Type, make sure Standard is selected.8. Enter the control engine’s IP address.

On hardware such as a SNAP PACthe IP address is usually written on a sticker on the side of the unit. If an IP address has not been assigned to the control engine, see Opto 22 form 1704, the PAC Manager User’s Guide, for configuration instructions.

NOTE: In PAC Control Professional, a second IP address field is available, so you can designate a secondary communication path to the control engine should the primary one fail. For more information, see “Using Ethernet Link Redundancy in PAC Control” on page 102.

9. Make sure that you have not changed the values in the Port, Retries, and Timeout fields, and then click OK.

The newly configured control engine appears in the Select Control Engine dialog box.



10. Click the new Cookie Controller control engine to select it, and then click OK.

The new control engine appears in the Configure Control Engines dialog box.

Since you have only one configured control engine at this point, it is automatically set as the active control engine. If there were more than one control engine, you would have to select it and click Set Active to load it into the Active Engine field.

11. Click OK to close the Configure Control Engines dialog box.

On the Strategy Tree, the new control engine appears as the first entry in the Control Engines folder.

Compiling the StrategyThe simplest way to compile a strategy is to enter Debug mode. The strategy is saved and compiled before changing modes.

NOTE: The remainder of the tutorial is designed to work with the controller and I/O on a SNAP PAC Learning Center. For more information, go to the Opto 22 website, www.Opto22.com and search on the part number, SNAP-PACLC.

1. Click the Debug mode button on the toolbar (or select Debug from the Mode menu).

2. In the Save Strategy dialog box, click Yes to save the strategy.3. If you see a Powerup Clear Expected message, click OK.

You may see a Download Warning message like this one:

COMPILING THE STRATEGY


Or you may see a message that the control engine’s memory has been cleared.

4. Click Yes to proceed.

Two additional dialog boxes appear. The first dialog displays the progress as the strategy is compiled. The second dialog shows progress as the strategy is downloaded to the control engine.

Assuming the strategy was compiled and downloaded successfully, you are now in Debug mode.

In the PAC Control window, you’ll notice that the Debug toolbar is now available. The mode is shown at the bottom of the main window. The open chart window shows that the strategy is stopped, as shown in the following figure:



Running the StrategyIn Debug mode, we’re going to run our strategy and examine it. We’ll see how the strategy run affects variables, how the command blocks are executed, and so on. The first chart to run in any strategy is the Powerup chart, so we’ll look at it first. 1. Double-click the Powerup chart on the Strategy Tree. When it opens, notice that it says

Stopped at the bottom left.2. Click the Run Strategy button .

A progress window appears, perhaps only briefly. And at the bottom of the chart window, the word Stopped changes to Running. Let’s try pausing the program to see where we are.

3. Click the Pause Chart button .

Debug toolbar buttons

Mode

Strategy status

RUNNING THE STRATEGY


The hatch marks on the Start? block indicate that this command block was about to be executed when we clicked Pause. Apparently the program isn’t getting past this block. Notice that the False exit routes right back to the top of the Start? block, while the True exit moves on to Start Charts. We can see that if the start flag had been true (non-zero), the program would have gone right into the Start Charts block. Since we didn’t get that far, the start flag must be zero.

And in fact it is. We planned it that way because we wanted someone (for example, a factory operator) to start the process intentionally. We can simulate this ourselves in PAC Control by manually setting the flag to a non-zero value.

4. Double-click the bStartFlag variable on the Strategy Tree.

A little box appears.

In this dialog box you can view the variable value, but you cannot change it unless you maximize the dialog box.

5. Click the Maximize button.

Maximize button



This dialog box displays current information on the variable bStartFlag. You can see that the variable is initialized to zero on strategy download.

6. Highlight the value zero in the dialog box and type 1 to replace it.

The field turns purple, indicating a change has been made but not implemented.

7. Click Apply to implement the change. Click the Minimize button in the bStartFlag View Variable dialog box and move it out of the way. Click the Powerup tab to make the Powerup chart the active window.

Inspecting Messages

1. Look for a light-blue box in the status bar at the bottom of the window.

The status bar in the main PAC Control window tells you when an information, warning, or error message has been placed in the message queue. Messages can help in troubleshooting your strategy. In this example an Information message is in the message queue.

2. Click the box or select Control Engine > Messages to view the View Message Queue dialog box.

This message tells you that the I/O unit has powered up.

3. Close the dialog box to return to the Powerup chart.

Stepping Through the ChartNow let’s step through the chart to see what’s happening.

1. Click inside the Powerup chart, and then click the Step Over button .

The hatch marks move from Start? to Start Charts. We’ve just moved (stepped) to the next block.

2. Click the button again.

PAC Control executes the Start Charts block and steps to the next command block. Since there are no more blocks in this chart, we are actually exiting this chart and



moving on to new instructions in another chart. The Powerup chart has stopped, and you can see the word Stopped at the bottom left of the chart.

In the View Variable dialog box, the bStartFlag value reverts to zero, because the Start Charts block set the flag back to zero.

3. Close the bStartFlag View Variable dialog box. In the Powerup chart window, click the Pause Chart button to turn stepping off.

Then close the Powerup chart.

4. Double-click the Charts folder on the Strategy Tree.

The View Chart Status dialog box appears.

This dialog box shows us all the charts in our strategy. As you can see, four of the charts are running, and one (Powerup) is stopped.

Powerup is stopped because it has already done its job. Let’s check the running charts.

5. Close the View Chart Status dialog box and click inside the Dough_Chip_Control chart again.

6. If your mouse has a wheel, hold down the CTRL key and move the mouse wheel up or down to change the zoom.

If your mouse doesn’t have a wheel, there are several other ways to zoom out, too. You can right-click on the chart and select Zoom from the pop-up menu. You can select Zoom Out from the View menu. You can press the + or - keys on the keyboard. After zooming out, the chart looks something like this:



You can zoom back in if you wish by holding down the CTRL key and moving the mouse wheel down or one of the other methods.

The chart’s status bar indicates that it is running, but we can’t see much happening.

7. Click the Pause Chart button .

One of the command blocks appears with hatch marks.

8. Now click the Step Over button .

The next command block is hatched.

9. Continue clicking and watch how the program proceeds from Speed OK? to Drop Dough to Drop Chips to Back to ‘Speed OK?’ and back up to Speed OK?

A pulsating green border appears around a block when the commands inside the block are being executed. While you are stepping through, and anytime the Pause Chart button is clicked, the chart status indicates Step On.

10. Click the Pause Chart button again to run the strategy at full speed.

Step Off now appears in the chart status bar.

Auto SteppingThe final stepping option is auto stepping. You can select this option whether or not the chart is currently paused.

1. Click the Auto Step Chart button and watch the program move from block to block.

At one time or another, your chart looks like this:



Notice that in the PAC Control toolbar, the Run and Auto Step Chart buttons are depressed. The chart status bar shows us the chart is running and in Step Auto mode. The time indicator to the right of Break Off shows the time it took for the most recent block to execute.

2. Click the Auto Step Chart button again to end auto stepping.

Step Off appears, indicating the program is again running without interruption.

Now let’s see how many cookies we’ve produced to this point.

3. On the Strategy Tree, double-click the numeric variable nCookie_Counter.

The Value field should increase every time a cookie is produced, adding to the total number of cookies produced since the strategy run began. The nCookie_Counter above shows this figure as 42. (Yours may be different.)

But nCookie_Counter tells us the total number of cookies put on the conveyor belt, without considering that some of them may be rejected by the inspection station. We need to subtract the number of bad cookies so that nCookie_Counter keeps track of the number of cookies sent out the door, not just sent to the oven.

4. Close the nCookie_Counter View Variable window and click the Configure mode button on the toolbar.

5. Double-click the Oven_Inspection_Control chart on the Strategy Tree to open it.

The chart window looks something like this:



Near the bottom of the chart, the Reject Cookie? block determines whether a bad cookie has been found. If one has, the strategy moves to the next block, Blow Off, which is where the bad cookie gets blown off the conveyor. When that happens, we want to decrement the nCookie_Counter variable.

6. Double-click the Blow Off block to open its instructions window:

This command block is executed only when a bad cookie has been found. This block first resets the on-latch triggered by the bad cookie, so that the next cookie won’t be marked bad, too. The block then turns on the reject valve. The valve stays on for two seconds before being shut off. Let’s decrement the counter after the cookie is gone and the valve is shut.

7. Scroll down and click on the open spot, below the other instructions.

The highlighted line marks the position of the next command to be added.

8. Click Add.



You can use PAC Control without a mouse, and to demonstrate how, we’ll use only the keyboard to enter data in this dialog box.

9. Type dec in the Instruction field.

The Decrement Variable command appears, since it’s the first command that starts with that text pattern. This is the command we want to use.

10. Press TAB twice to move to the Comment field. Type in a comment.11. Press TAB again to move to the Type field. Press the down arrow on your keyboard twice

to select Integer 32 Variable. 12. Press TAB again to advance to the Name field, and then press the down arrow until you

see nCookie_Counter. 13. Press TAB again and notice that an outline appears on the OK button.

An outlined button means that pressing the space bar or ENTER is equivalent to clicking the button.

Now the dialog box looks like this:

14. Press ENTER.

The dialog box closes and the new command appears in the Instructions window.



15. Click Close to return to the Oven_Inspection_Control chart.

Compiling and Downloading the ChangeNow we’ll compile and download the modified strategy.

1. Click the Debug mode button on the toolbar.

A message box appears, warning you that changes have been detected and asking if you want to save them before downloading.

2. Click Yes to continue.

Another warning notes that the strategy name, check sum, or timestamp differs from that in the control engine and asks if you want to continue.

3. Click Yes.4. On the toolbar, click the Run Strategy button . In the Strategy Tree, double-click the

bStartFlag variable. Maximize the dialog box, change the value to 1, and click Apply. Close the dialog box.

5. Click inside the Oven_Inspection_Control chart to make it the active chart, and then click the Auto Step Chart button.

You see three blocks being processed: Speed OK?, Oven On, and Reject Cookie? The strategy doesn’t move into the Blow Off block. That’s because an inspector has to flag bad cookies, but we don’t have an inspector right now. So we’ll simulate what would happen by tripping the digital input that flags a bad cookie.

6. In the Oven_Inspection_Control chart, click the Auto Step Chart button again to stop auto stepping.

Step Auto changes to Step Off in the status bar.

7. Click the Pause Chart button.

Step Off changes to Step On.

8. Click the Breakpoint tool and click once on the Blow Off block.

New command

COMPILING AND DOWNLOADING THE CHANGE


A breakpoint hand appears on the block.

9. Click the right mouse button or press ESC to release the tool. Notice that Break On now appears in the chart status bar.

10. Click the Breakpoint tool and click once on the Blow Off block.

A red box appears around the Blow Off block, and Break On now appears in the chart status bar.

11. Click the Dough_Chip_Control tab at the bottom of the PAC Control main window.

The chart appears.

12. Click the Pause Chart button to pause the chart.

Break On

Oven_Inspection_Control



Using a Watch WindowTo see clearly what we’re doing, we’ll create a watch window to monitor cookie production.1. In the Strategy Tree, double-click nCookie_Counter.

The value is frozen at some number, such as the 74 shown above. Since the counter is no longer increasing, we can see that cookie production has temporarily stopped.

2. Maximize the dialog box.

3. Click Add Watch.4. Click Watch.

USING A WATCH WINDOW


Since there is no watch window available to select, we’ll create one.

5. Click New.

6. Make sure the My Cookies directory appears in the Look in field. Type a name for the watch window in the File name field. Then click Open.

The watch window name appears in the Add Watch dialog box, and the new watch window appears behind it.

7. In the Add Watch Entry dialog box, click OK. Close the nCookie_Counter view variable dialog box.

The new watch window looks something like this:



Since we want to be able to see chart windows as well as the watch window, let’s dock the watch window at the bottom.

8. In the watch window, click the docking icon in the upper-right corner.

The watch window moves to the bottom of the main window.

Docking iconWatch window



Now we’ll trip the latch that signals a bad cookie.

9. On the Strategy Tree, under the I/O Units folder at the bottom of the window, expand Mixed_IO_Unit by clicking the plus sign at the left of the name.

You see a folder named Points.

10. Expand the Points folder to display the digital I/O points configured for this I/O unit.

11. Double-click diInspectionPassFailSwitch.

Docked watch window

Points folder



12. In the minimized dialog box, click the maximize button.

NOTE: Don’t worry if the red error message “I/O unit not configured” or XVAL values appear in this dialog box. This occurs because the strategy is configured for sample hardware that probably doesn’t correspond to your actual I/O units and modules. PAC Control can’t locate this hardware. That’s okay for this example.

When an inspection finds a bad cookie, the on-latch attached to the I/O point diInspectionPassFailSwitch is supposed to go on. We’re going to trip it manually.

13. Click one of the arrows in the On-Latch IVAL field to change it to On. Also make sure that the Enable comm field says No.

The dialog box should look like this:

14. Click Apply.

The On-Latch IVAL field turns green after a second or two, indicating the latch is on.

15. Click Add Watch.

We’ll add the variable to our watch window, so we can see what happens.

Maximize button

On-latch On



16. In the Add Watch dialog box, leave all portions checked. Click OK to add the variable to the Cookie Watch window. Close the view point dialog box.

17. In the Cookie Watch window, click the plus sign next to (02) diInspectionPassFailSwitch.

Your screen may show only part of the words.

18. Move your cursor over the right side of the Name column until the cursor changes shape. Then click and drag the column to make it wider, until you can see all the words.

19. Click in the Oven_Inspection_Control chart to make it active, and move the scroll bars until you can see the Blow Off block at the bottom.

Your window now looks something like this:

20. Click the Step Over button as many times as it takes to get the hatch marks to the Blow Off block. Now watch the nCookie_Counter IVAL value in the watch window as you click the button again.



A bad cookie was found, so the counter was decreased by one. At the same time, the on-latch was reset to Off, as you can also see in the watch window.

21. Click the Auto Step Chart button to go back to auto stepping.

The counter does not decrease again, because the on-latch is no longer set. But the counter won’t increase until we start the Dough_Chip_Control chart again.

22. Click the Dough_Chip_Control chart tab. Click the Pause Chart button to unpause the chart. Verify that Step On changes to Step Off in the chart status bar.

The watch window shows the nCookie_Counter value going up again.

Counter decreased by oneOn-latch reset to Off

CLOSING THE STRATEGY AND EXITING


Closing the Strategy and ExitingBefore we finish this tutorial, you may want to explore the sample strategy on your own. You can double-click items in the Strategy Tree or open up other charts to see what they do. You can also double-click command blocks to see what they contain.1. When you’re ready to stop, click the Stop Strategy button in the toolbar.

This action prevents the strategy from running continuously unattended on the control engine.

2. To close the strategy, select File > Close Strategy; or select File > Exit to quit PAC Control. If dialog boxes ask whether you want to remove breakpoints and take charts out of stepping mode, click Yes.

What’s Next?Your introduction to PAC Control is now complete. Using the sample Cookies strategy, you have learned how to:

• Open, save, and close a strategy

• Work with the Strategy Tree

• Work with charts and add commands in blocks

• Configure a control engine

• Compile, run, step through, and add breakpoints to a strategy

• Make an online change

• Use a watch window to monitor variables and I/O points.

The rest of this book expands on the knowledge you’ve just acquired. Now may be a good time to look at the table of contents or thumb through the book and familiarize yourself with its contents. Some sections you may want to read; others you’ll probably just refer to as needed.


3: 3: What Is PAC Control?Chapter 3

3: What Is PAC Control?

IntroductionThe tutorial in Chapter 2 introduced you to PAC Control without explaining much about it. In this chapter we’ll learn more about PAC Control and see its main windows and toolbars.

In this ChapterAbout PAC Control ......................................................47General Control Concepts........................................49PAC Control Terminology .........................................51PAC Control Main Window......................................56Windows and Dialog Boxes in PAC Control .....61Customizing PAC Control for Your Needs .........69Online Help ....................................................................72

About PAC ControlPAC Control is a programming language based on flowcharts. Whether you have PAC Control Basic or PAC Control Professional, you use PAC Control to develop software that monitors and controls all kinds of equipment and sensors, from a simple heating system to a complex factory. The software you develop controls the Opto 22 hardware that runs your heating system or factory.

The diagram below shows how PAC Control on your PC can work with the hardware in your control system. This example shows a small system; yours may be even smaller or considerably larger and more complex. The diagram uses a SNAP-PAC-S1 as the control engine. Input/output (I/O) points on the subordinate SNAP PAC I/O units monitor and control the analog, digital, and serial devices connected to them. All these terms are defined in the following pages.

ABOUT PAC CONTROL


Control System Example

PAC DisplayViewing, Trending, Alarming

PAC ControlProgramming, Debugging

SNAP PAC S-series controllerRuns strategy, controls all I/O

SNAP PAC I/O unit

Pump (On or Off ) (Digital output)

Tank Level (Analog input)

Barcode Reader (Serial device)

Photo Sensor (Digital input)

Conveyor

Furnace Temperature (Thermocouple) (Analog input)

Fuel Pump (Analog output)

SNAP PAC I/O unit

SNAP PAC I/O unit

CHAPTER 3: WHAT IS PAC CONTROL?


General Control Concepts

AutomationAutomation is a way of adding intelligence to an industrial process. When you automate a process, you are less dependent on human action to carry out the process. The process generally becomes faster, more accurate, and more reliable. For example, take a look at the tank level and pump combination in the diagram on the previous page. Instead of having a person watch the level in the tank and turn the pump on or off when the level gets too low or too high, you can automate the process by installing a processor and I/O. The processor and I/O respond in milliseconds and are on the job 24 hours a day.

Control EnginesThese processors are programmable electronic components that provide the intelligence required for automation. In an Opto 22 PAC Control system, the processor is called a control engine, and it is built into the Opto 22 controller.

Using PAC Control, you create a set of instructions (a software program) that tells the control engine how every aspect of a process should work. Using PAC Control, you download the software program to a Opto 22 SNAP PAC controller, and the controller runs it as a stand-alone application. Since the instruction set is stored in the processor’s electronic memory, much as a small computer would store it, the PC can be turned off or used for other operations while the control engine in the processor runs the program. And the instructions can be easily modified when necessary.

In the diagram on the previous page, one SNAP PAC S-series controller runs the program that controls the three areas of automation.

Digital and Analog Inputs and OutputsAn industrial process can include many different hardware components: switches, pumps, tanks, valves, furnaces, conveyors, photo sensors, thermocouples, and so on. All the components communicate with the control engine in the controller by way of input/output (I/O) points.

Input points are wired to hardware that brings information into the control engine from the process. Examples of devices that can be wired to input points are thermocouples, switches, and sensors. The control engine takes the information from the input points—such as whether a switch is on or what temperature is registered on a sensor—processes it using the software instruction set, and returns information to the process through output points.

Output points are wired to hardware that receives information from the control engine and uses this information to control components of the process. For example, lights,

KEY FEATURES


motors, and valves are all devices that can be wired to output points. Using an output point, the control engine might turn on a light or open a valve.

There are two types of I/O points, digital and analog:

• Digital points can be either on or off (True or False). Push buttons and LEDs are examples of digital devices. An LED is either on or off; it has no other possible state.

In the Control System Example on page 48, the photo sensor is an example of a digital input device. The photo sensor is either on or off. When it turns off as the sheet passes through its beam, the digital I/O module tells the control engine it is off, and the control engine responds as programmed to stamp the sheet.

The pump is an example of a digital output device. Based on information from the tank level input, the control engine turns the pump on or off as programmed.

• Analog points have a range of possible values. Temperature and pressure are examples of analog information. Temperature might be any number in a range, -2 or 31.65 or 70.1 or many other possible numbers.

In the Control System Example on page 48, the tank level sensor is an analog input device. It registers the changing level of water in the tank and reports the level to the control engine, which responds by turning the pump on or off.

The fuel pump is an example of an analog output device. Based on information about the temperature in the furnace, the control engine adjusts the pressure of fuel through the pump as programmed.

SNAP Special-Purpose I/O ModulesIn the PAC Control system, some I/O modules do not contain standard analog or digital input/output points, but are used for special purposes.

SNAP serial communication modules provide two channels of serial data. Through these channels, data can be sent to and received from a serial device. In the Control System Example on page 48, the barcode reader is an example of a serial device.

SNAP high-density digital (HDD) modules provide 32 channels of digital input or 32 channels of digital output in one module. Any of the digital input or output devices shown in the diagram could be wired to HDD modules rather than standard 4-channel digital modules.

Key FeaturesSee the following topics for some of PAC Control key features:

• “Copying I/O Configurations” on page 121

A configuration file allows you to copy an I/O configuration from one strategy to another. Or, using PAC Manager, you can send the configuration to multiple I/O units at the same time.



• “Using Network Segmenting in PAC Control” on page 101

Using the two independent Ethernet network interfaces on a SNAP PAC controller, you can segment the control network from the company network.

• “Using Ethernet Link Redundancy in PAC Control” on page 102

(Pro only) If you are using SNAP PAC controllers and PAC Control Professional, you can use Ethernet link redundancy to set up alternate network links.

• “Persistent Data” on page 233

You can configure the data in most variables to be persistent. The variable’s value is saved in the controller’s memory; it does not change when the strategy is run, stopped, or started, and it does not change if the strategy is changed and downloaded again.

• “Pointer Commands” on page 306

For advanced programming, you can create pointers that store the memory address of a variable or some other PAC Control item, such as a chart, an I/O point, or a PID loop. You can perform any operation on the pointer that you could perform on the object the pointer points to.

• “Setting Initial Values in Variables and Tables During Strategy Download” on page 238

When you are adding table variables in PAC Control, you can set all table elements to one initial value. Or, you set each individual table element to its own value by creating an initialization file to download with your PAC Control strategy.

• “12: Using Subroutines” on page 353

You can use subroutines that are independent from strategies, but that can be called from any strategy. Subroutines offer two ways to work with variables and other logical elements: they can be passed in or they can be local to the subroutine.

• “Configuring PID Loops” on page 141

A proportional integral derivative (PID) control system (often referred to as a PID loop) monitors a process variable, compares the variable’s current value to a desired value (a setpoint), and calculates an output to correct error between the setpoint and the variable. Because the calculation is complex, it is done by a mathematical formula, or algorithm, that you can then adjust (tune) for each PID loop.

PAC Control Terminology

action block

Action blocks are rectangular blocks in a flowchart that contain one or more instructions (actions) that do the work of the strategy, such as turning things on or off, setting variables, and so on. Several instructions can be placed in one action block. Action blocks can have many entrances, but only one exit.

PAC CONTROL TERMINOLOGY


analog point

Analog points have a range of possible values. Temperature and pressure are examples of analog information. Temperature might be any number in a range, -2 or 31.65 or 70.1 or many other possible numbers. Analog points can be either inputs (such as a tank level sensor) or outputs (such as a fuel pump).

blocks

A chart is made up of action blocks, condition blocks, continue blocks, and OptoScript blocks connected by arrows, which show how the process flows. A chart used with redundant controllers also has sync blocks.

sync block

The sync block tool is only visible when controller redundancy support is enabled. A sync block is used to synchronize redundant controllers at strategic locations in a transactional chart (a chart that contains sync blocks). For more information, see form 1831, the SNAP PAC Redundancy Option User’s Guide.

condition block

Condition blocks are diamond-shaped blocks in a flowchart that contain questions (conditions) that control the logical flow of a strategy. Condition blocks can have many entrances, but only two exits: True and False. The block can contain more than one condition, and you can use AND or OR to indicate whether all conditions must be true to exit True, or whether any one condition must be true to exit True.

continue block

Continue blocks are oval-shaped blocks in a flowchart that route the flow of execution to an action, condition, or OptoScript block. They do not contain any instructions, but store only the name of the next block to execute. Continue blocks can have many entrances, but no exits, since the exit is defined within the block. Continue blocks avoid awkward connections between two blocks that are far apart.

digital point

Digital points can be either on or off (true or false). Push buttons and LEDs are examples of digital devices: an LED is either on or off; it has no other possible state. Digital points can be either inputs (such as a photo sensor) or outputs (such as a pump).

Action block

Condition block

OptoScript block

Continue block

Checkpoint block



external value

The external value (XVAL) is the real-world value measured or set by an I/O point. The PAC Control strategy reads and writes only to internal values, and transfers internal values to external values if communication to the associated I/O unit is enabled.

flowcharts

Since most control applications are complex, the strategy typically consists of a series of process flowcharts, or charts, that all work together. Each chart controls one aspect of the strategy—one piece of the automated process. Together, all the charts constitute the strategy. The total number of charts in a strategy is limited only by the amount of memory available in the control engine.

A chart can be running, suspended, or stopped. A running chart is actively performing its assigned task. A suspended chart is temporarily paused. A stopped chart is inactive. Every chart in a PAC Control strategy can change the status of any other chart in the strategy, yet every chart is independent of every other chart. Any combination of charts can be running simultaneously, up to the maximum limit allowed on the control engine. (See also, multitasking.)

Every strategy automatically contains a Powerup chart. The Powerup chart is automatically started when the strategy begins running, so it starts other charts. All other charts you create, based on the needs of your process.

input point

Input points are wired to hardware that brings information into the brain from the process. Examples of devices that can be wired to input points are thermocouples, switches, and sensors. The control engine in the brain takes the information from the input points—such as whether a switch is on or what temperature is registered—processes it using commands in the strategy, and returns information to the process through output points.

• A floating point (or float) is a numeric value that contains a decimal point, such as 3.14159, 1.0, or 1234.2. A good example of a float variable is one that stores readings from an analog input, such as a thermocouple.

• An integer is a whole number with no fractional part. Examples of integer values are -1, 0, 1, 999, or -456. The state of a switch, for example, could be stored in an integer variable as 1 (on) or 0 (off ).

• A timer stores elapsed time in units of seconds with resolution in milliseconds. Up timers count up from zero, and down timers start from a value you set and count down to zero. For example, you could set a down timer to make sure a value is updated at precise intervals.

• A string stores text and any combination of ASCII characters, including control codes and extended characters. For instance, a string variable might be used to send information to a display for an operator to see.

A string variable can contain numeric characters, but they no longer act as numbers. To use them in calculations, you must convert them into floating point or integer

PAC CONTROL TERMINOLOGY


numbers. And a numeric value to be displayed on a screen must be converted into a string first.

• A pointer does not store the value of a variable; instead, it stores the memory address of a variable or some other PAC Control item, such as a chart or an I/O point.

• Communication handles store parameters needed for communication with other devices.

You can use variables that are individual pieces of information, and you can also use table variables, which are groups of related information in the form of a table.

instructions (commands)

PAC Control commands, or instructions, tell the control engine what to do at each step in the flowchart to control the process. Each block in a chart contains one or more instructions, such as Convert Number to String or Start Counter or Chart Running?

Commands are in two forms: Actions and Conditions.

• Action commands do something in the process; for example, Convert Number to String and Start Counter are both action commands. On the flowchart they appear as instructions in action blocks, which are rectangular in shape. They may also appear in hexagonal OptoScripts.

• Condition commands check a condition and are in the form of a question. Chart Running? and Variable False? are examples of condition commands. They appear as instructions in condition blocks, which are diamond-shaped, or in hexagonal OptoScript blocks. Condition commands are questions that always have two possible answers, either yes or no (true or false). The answer determines the flow of logic and what happens next in the chart.

internal value

The internal value (IVAL) is the value read or written by the PAC Control strategy. Internal values are transferred to external values only when communication to the I/O unit is enabled.

multitasking

The control engine can run several charts seemingly at once, each performing a different task, through a time-slicing technique called multitasking (also called multicharting). Opto 22 SNAP PAC R-series controllers can run up to 16 charts plus one host task simultaneously; SNAP-PAC S-series controllers can run up to 32 charts plus one host task simultaneously. The host task is an invisible chart used to communicate to a PC, which may be running PAC Control in Debug mode or PAC Display.

Each chart in a running or suspended state counts toward the total that can run simultaneously. Charts that are stopped do not. When the Powerup chart is running, it also counts.



The actual order and timing for running tasks is not deterministic—that is, it is not always the same, but depends on priorities at any given time. For example, communication may sometimes take a higher priority than a running chart.

OptoScript block

OptoScript blocks are hexagonal blocks in a flowchart that contain OptoScript code. OptoScript is a procedural language that can simplify tasks such as math computations, string handling, and complex loops and conditions. OptoScript blocks can have more than one entrance but only one exit.

output point

Output points are wired to hardware that receives information from the brain and uses this information to control components of the process. For example, lights, motors, and valves are all devices that can be wired to output points. Using an output point, the control engine in the brain might turn on a light or open a valve.

pointer

A pointer does not store the value of a variable; instead, it stores the memory address of a variable or some other PAC Control item, such as a chart, an I/O point, or a PID loop. You can perform any operation on the pointer that you could perform on the object the pointer points to. Pointers are an advanced programming feature and are very powerful, but they also complicate programming and debugging.

Because pointers can point to any data type, pointer tables can store an assortment of data types in a single table.

Pointers allow one level of indirection within PAC Control; a pointer cannot point to another pointer. After you add a pointer through the “Add Variable Dialog Box” on page 234, you can use it wherever the object itself would be used.

strategy

The software program you create using PAC Control Basic or PAC Control Professional. The strategy includes all the definitions and instructions (commands) necessary to control the process that one Opto 22 controller handles. Since most control processes are complex, the strategy typically consists of a series of process flowcharts that all work together, with each chart controlling one piece of the automated process. You may have several PAC Control systems, each controlling a different process and therefore running different strategies. Or you may have two or more PAC Control systems controlling identical processes in different areas and running the same strategy.

variables

A variable is a holding place that represents a piece of information in a strategy, such as the parameters for communication, temperature reported by a thermocouple, the name of a chart, or a group of words and numbers to be sent to a display. The information a variable represents is called the value of the variable. As a strategy runs, the variable’s name remains

PAC CONTROL MAIN WINDOW


the same, but its value may change. For example, the value of a variable named Oven_Temperature may change several times while its strategy is running, but its name remains Oven_Temperature.

A variable stores one of six types of data: floating point, integer, timer, string, pointer, or communication handle. When you create the variable, you designate the type of data it contains.

The instruction shown below is for the condition block, Button D3 On? This block contains only one instruction. As you look at the chart, you can see that the answer to the question in the instruction determines whether the process flows to Turn LED D7 On or to Turn LED D7 Off.

PAC Control Main WindowWith a strategy open, the main window in PAC Control Basic and PAC Control Pro looks similar to this:

Instruction for the block named Button D3 On?



Since PAC Control uses standard Microsoft Windows conventions, you’ll recognize the title bar and menu bar and already be familiar with some of the menus, such as File, Edit, View, Window, and Help. This section discusses some things that may not be familiar.

Status BarThe status bar at the bottom of the window shows you information about PAC Control. When you move your mouse over the toolbar, a description of the button you’re pointing to appears in the status bar. The status bar indicates the mode PAC Control is in and indicates messages or errors helpful in debugging.

To hide or show the status bar, choose View > Status Bar. A check mark next to the menu item means the status bar will show; no check mark means it is hidden.

ModeYou can run PAC Control in three modes: Configure, Debug, or Online. The current mode is shown in the status bar, on the right. Toolbars and menus change depending on the mode.

• Configure mode is used to create, modify, save, and compile strategies, flowcharts, and subroutines; and to configure control engines, I/O, and variables.

• Debug mode is used to download, run, and debug strategies and to view control engine and communication status and errors while the strategy is running.

• Online mode is a scaled-down version of Configure mode, used to change a strategy while it is running. You cannot add variables and I/O in Online mode, but you can change ones that already exist.

PAC Control title barMenu bar

Toolbar

Strategy Tree

ModeStatus bar



NOTE: When you change a chart in Online mode, a new copy of that chart is downloaded to the control engine, but the old one is not deleted. After you have made a few online changes, the additional chart copies begin to take up memory. To avoid memory problems, be sure you stop the strategy after making several online changes and completely compile and download it to clear out old chart copies.

To change modes, choose the mode you want from the Mode menu, or click its button in the toolbar.

ToolbarsToolbars give you shortcuts for doing many things that also appear on menus. Toolbars in PAC Control include standard Windows buttons like New and Save as well as special buttons for PAC Control functions. The tools that you can use depend on which mode you’re in. Tools not currently available are grayed out.

The following toolbars are standard in PAC Control.

“Mode Selection Toolbar”

“Configure Mode and Online Mode Toolbar”

“Debug Mode Toolbar”

Mode Selection Toolbar

The mode selection tools are always available.

Configure Mode and Online Mode Toolbar

The following toolbar appears in configure mode and online mode.

In a smaller window, the toolbar looks like this.

Icon Description

Configuration Mode

Debug Mode

Online Mode



Debug Mode Toolbar

The following toolbar appears in debug mode.

In a smaller window, the debug toolbar looks like this.

Tool Name Tool Name

New Strategy Pan Tool

Open Strategy Action Block Tool

Save Strategy OptoScript Block Tool

Cut Condition Block Tool

Copy Continue Block Tool

Paste Checkpoint Block Tool

Delete Connect Tool

Find Text Tool

Find and Replace Compile Active View

Select Tool Compile All

Tool Name Tool Name

Run Strategy Over

Stop Strategy Out

Pause Chart Auto Step



Strategy TreeThe Strategy Tree opens when you open a strategy, and closing it is equivalent to closing the strategy. The Strategy Tree shows you all the elements of your strategy: control engines, flowcharts, subroutines, variables, I/O units and points, and PIDs.

The Strategy Tree works just like Windows Explorer: you can expand or collapse folders to view or hide what is in them. You can easily see what is in your strategy, open elements to change them by double-clicking them, or open a pop-up menu by right-clicking on an element.

Each element in the strategy is represented by a button, shown just to the left of its name. The table below shows the buttons and what they represent.

Into Breakpoint

Button Description Button Description

Control Engine Integer 32 Table

Chart Integer 64 Table

Subroutine String Table

Integer 32 Variable Pointer Table

Integer 64 Variable Digital I/O Unit

Tool Name Tool Name

Strategy tree



Windows and Dialog Boxes in PAC ControlWindows and dialog boxes in PAC Control follow Microsoft Windows standards. You can minimize, maximize, move, resize, and tile them as needed. See your Microsoft Windows documentation for information on how to do these things.

The following topics describe other useful features in PAC Control:

“Using Tabs to View Open Windows” on page 61

“Docking Windows” on page 63

“Zooming in a Chart or Subroutine Window” on page 64

“Redrawing a Chart or Subroutine Window” on page 66

“Changing Column Width in a Dialog Box” on page 67

“Sorting Data in a Dialog Box” on page 67

Using Tabs to View Open WindowsWhen multiple windows are open—especially if they are maximized—it can be difficult to know where you are, and windows can become lost behind each other. However, you can click the tabs at the bottom of the main PAC Control window to move among chart windows, subroutine windows, watch windows, and blocks you may be stepping through for debugging.

Float Variable Mixed I/O Unit

Down Timer Variable Analog Input Point

Up Timer Variable Digital Input Point

String Variable Analog Output Point

Communication Handle

Digital Output Point

Float Table PID Loop

Pointer Variable


WINDOWS AND DIALOG BOXES IN PAC CONTROL


The upper layer of tabs appears when you are stepping through your strategy in Debug mode. It acts as a kind of call stack to let you see how you got to the current block or command.

Gray tabs show open windows. Click a tab to bring its window into view.

White tabs show where you are when stepping through a chart or subroutine.



Docking WindowsYou can place the strategy Tree and watch windows where you want them (dock them) in the PAC Control main window. Docked windows do not have tabs but are contained in their own frames. PAC Control remembers their position the next time you open that strategy.

• To dock a window, click the docking icon in the window’s title bar.

The window moves to its own frame. (Compare the following figure with the one on page 56 to see the difference in the Strategy Tree window.)

This white tab shows you are stepping inside the Variable_Increase_ Notification subroutine, which was called by the Increment Counter action block on the gray tab at left. The gray Chart tab farther left shows the chart this action block is in. Click any tab to see how you got to where you are.

Click the arrow buttons to see tabs that are not visible or are only partly visible.



• To change the docked position, click and drag the window’s title bar to any edge of the main window.

• To change the docked window’s width or height, click and drag the edge of its frame in the direction you want.

• To free the window from its docked position, click the docking icon in its title bar.

Zooming in a Chart or Subroutine WindowYou can change the scale of any chart or subroutine window by using the zoom feature. There are several ways to zoom:

• Hold down CTRL key and move the mouse wheel up and down.

• Press the + or - keys on the keyboard.

• Right-click anywhere on a chart or subroutine window to display a pop-up menu. Select Zoom and choose In, Out, or Reset (to return the zoom to 100 percent).

• From the View menu, choose Zoom In, Zoom Out, or Zoom Reset.

• To pick the zoom percentage you want, click the zoom field at the bottom right of the window and choose one of the preset zoom levels. The “Zoom to fit” option resizes the chart to fit in the window.

NOTE: Zooming always takes place with reference to the center point of the window.

Here is a window at 50 percent zoom:

Docked strategy Tree



The same window at 200 percent zoom looks like this:

Panning a ChartThe pan tool allows you to easily pan around a flowchart.

1. Using the pan tool , click and hold to grab a portion of a chart.

You can access the pan tool either from the toolbar or by holding down the space bar and clicking the left mouse button.



2. Move the pan tool to a new position and release.

The chart moves to a new position.

Redrawing a Chart or Subroutine Window If you want to move quickly to a particular block, you can redraw a chart or subroutine window with any block at its center. 1. With a chart or subroutine open in the active window, select View > Center On Block,

or right-click in the chart or subroutine window and choose Center On Block from the pop-up menu.

The Center On Block dialog box appears, listing all blocks in the chart.

Pan tool

Pan tool



2. Double-click the block you want, or click it once and click OK.

The chart or subroutine is redrawn with the selected block in the center of the window.

Changing Column Width in a Dialog BoxMany dialog boxes include several columns of information. To see all the data in some columns, you may need to make columns wider.

• To widen or narrow a column, click the right edge of the column label and drag it horizontally.

• To resize a column to the exact width of its longest entry, double-click the line that separates the column from the one on its right.

Sorting Data in a Dialog BoxIn some dialog boxes with columns of data, you can sort the information in the way you want to see it. The Center On Block dialog box provides an example. The blocks in this dialog box normally appear in alphabetical order by the block name.

Click and drag



• To sort by block number instead, click the Block Id column label.

• To sort in the opposite order (descending numbers instead of ascending numbers), click the Block Id column label again.

Some dialog boxes don’t allow custom sorting. If you click a column label in these dialog boxes, nothing happens.



Customizing PAC Control for Your Needs

Setting Decimal, Binary, or Hex Display ModeYou can set up PAC Control to show the values of all integers and integer tables in decimal (the default), binary, or hexadecimal (hex) format. Binary and hex formats help you use masks. Hex view is available in all modes: Configure, Debug, and Online.

The default view is in decimal notation, as shown in the following figure.

To view integers and integer tables in binary view, choose View > Binary Integer Display, or click the DEC button and choose Binary. The integers appear as shown below.

To view integers and integer tables in hex view, click BIN in the dialog box, and then select Hexadecimal. Here’s how the integers appear in hex:

To return to decimal view, click HEX and then select Decimal.

Setting Hex String View

You can also set strings to appear in hex notation. Here is the View Variable window showing a string in regular notation:

Decimalview

Binary view. All the bits cannot be shown at once.

Hex view. The 0x before the number indicates that the number is in hex.

CUSTOMIZING PAC CONTROL FOR YOUR NEEDS


To change to hex notation, click the ASCII button on the dialog box. Here’s how the string appears in hex:

Setting Up Applications to Launch from PAC ControlYou may find it useful to launch other software applications directly from PAC Control. For example, you may want to launch PAC Display, Notepad, or the Calculator from PAC Control. You can set up PAC Control so that these applications appear in the Tools menu.

NOTE: If you launch an application from within PAC Control when that application is already running, a second instance of the application may open. It depends on the application; some check to see whether the application is already running, and some do not.

1. With PAC Control open, choose Tools > Customize.

The Customize dialog box appears.



2. Click Add.3. In the Menu Text field, type the name of the application as you want it to appear in the

Tools menu.4. In the Command field, type the path for the application’s executable file, or click the

browse button and navigate to the file. 5. (Optional) In the Arguments field, type any necessary command line parameters.6. (Optional) In the Initial Directory field, type the directory the application should default

to when it runs.

For example, this is the directory the application would show when you open or save files.

7. Repeat the steps to add other applications. To change an application’s position in the menu list, highlight it and click the Move Up or Move Down keys.

8. When you have finished adding applications, click OK.

You return to the PAC Control main window, and the applications you’ve added now appear in the Tools menu.

Keyboard and Mouse ShortcutsUse the following keyboard and mouse shortcuts to view and navigate a chart.

Action Shortcut Action Shortcut

Center on Block 0 0 or Numeric Keypad 0 Move to Bottom Left Numeric Keypad 1

Move to Top Left Numeric Keypad 7 Move to Bottom Numeric Keypad 2

Move to Top Numeric Keypad 8 Move to Bottom Right Numeric Keypad 3

Move to Top Right Numeric Keypad 9 Zoom to Fit and Center F

Move to Left Numeric Keypad 4 Zoom to 100% Z

Move to Center Numeric Keypad 5 Pan Space + Left Mouse Button

Move to Right Numeric Keypad 6 Block Preview Middle-click on a block

ONLINE HELP


Online HelpTo open online Help, choose Help > Help Topics, or click the Help button in any dialog box. Help buttons in dialog boxes are context sensitive and provide help specifically on that dialog box. Buttons labeled “Command Help” give specific information on the command (instruction) you are currently using.

For brief explanations of buttons, move your mouse over the button and look in the status bar.

In Action and Condition Instructions dialog boxes, let your mouse rest for a second on an instruction (command), and you’ll see a list of the variable types used in that command. (To show or hide the variable types list, in Configure mode, choose PAC Control Options > Show/Hide Instruction Type Information.)

To open online copies of PAC Control manuals and quick reference cards, choose Help > Manuals. You will need Adobe Acrobat Reader to open these files. You can also find information, documents, and support on the Opto 22 website by choosing Help > Opto 22 on the Web.


4: 4: Designing Your StrategyChapter 4

4: Designing Your Strategy

IntroductionThis chapter introduces you to PAC Control programming—how to design a PAC Control strategy to control your automated process. For additional important information on using PAC Control commands (instructions) to program your strategy effectively, see page 255 and the individual command information in the PAC Control Command Reference.

NOTE: Because our focus in PAC Project is on the SNAP PAC System, PAC Control initially shows only SNAP PAC I/O units and the commands used with them. When you’re using the SNAP PAC system only, hiding legacy I/O units and commands makes it simpler and less confusing to build your strategy. However, the legacy capabilities are still there and can be made visible in a specific strategy as needed. For information, see “Legacy Options” on page 207.

In this ChapterSteps to Design.............................................................73Basic Rules ......................................................................81Instruction Examples .................................................84Optimizing Throughput ...........................................95

Steps to DesignHow do you get from your real-world control problem to a working PAC Control strategy that solves it? Here’s an outline of the basic approach; we’ll fill in the details on the following pages.

First, solve the problem.

• Define the problem.

– What am I trying to do?

– What inputs and data do I have to work with?

– What do the outputs have to be?

STEPS TO DESIGN


– How many times does the process have to be repeated?

• Design a logical sequence of steps to solve the problem.

– Break down the larger process task into sub-process tasks.

– Break down the sub-process tasks into detailed steps.

• Test the steps.

Next, build the strategy.

• Configure hardware.

– Control Engines

– I/O units

– I/O points

• Determine necessary variables and configure them.

• Create charts, one for each sub-process, and add instructions.

• Compile and debug each chart.

• Compile and debug the whole strategy.

Finally, use and improve the strategy.

Now let’s take a look at each of these steps in order.

Solving the ProblemYou can avoid a lot of extra time and rework if you define and solve your problem before you ever start building a flowchart in PAC Control.

Defining the Problem

Suppose, for example, you want to automate a simple lawn sprinkler system. Start by asking yourself (or others) questions about the control process you’re trying to do.

What are you trying to do? Start with the big picture and work down to the smaller details.

• Big picture: I’m trying to control this sprinkler system.

• Smaller details:

– The sprinklers should turn on every Sunday and every Wednesday.

– They should not turn on if it’s raining.

– They should start at six o’clock in the morning.

– They need to run for 15 minutes.

CHAPTER 4: DESIGNING YOUR STRATEGY


What inputs and data do you have to work with? List all the inputs. Describe the data they provide. Check for any inputs or data you need but don’t have.

What do the outputs need to be? List all the outputs. Describe the results that are needed. Check for any outputs you need but don’t have.

How many times does the process have to be repeated? Our example is a simple sprinkler system in which the process happens twice a week on certain days. In a more complex system, however, you might have one section of the sprinklers turn on, followed by other sections, repeating the process several times in different areas and then repeating the whole pattern on certain days.

Designing a Logical Sequence of Steps to Solve the Problem

Now that you’ve determined what you’re trying to do and what your inputs, data, and outputs look like, you’re ready to outline the steps needed to solve the control problem. Think about how you would do the job if you were doing it by hand. Again, work from the top down, starting with big steps and then breaking those big steps into smaller steps.

Input Data the input provides

Hygrometer Humidity (percentage from 0–100%)

Day Day of the week (Sunday through Saturday)

Time Hour of the day (24-hour clock)

Sprinkler status Whether sprinklers are currently running (on or off)

Input from timer Length of time sprinklers have been on (in minutes)

Output What it does

Sprinkler switch Turns sprinklers on or off

Timer control Sets timer

Sprinkler Control SystemEvery day at 6:00 a.m.:1. Check the day and the weather.

1. Check the day and the weather.Read the day of the week. If it’s Sunday or Wednesday, read the hygrometer.

2. If it’s raining, leave them off.If the hygrometer says 100%, check to make sure sprinklers are off.If they’re on, turn them off.

3. If it’s the right day and it’s dry, turn them on.If it’s Sunday or Wednesday and if the hygrometer says 99% or below, turn sprinklers on.Start the timer.When they’ve been on for 15 minutes, turn them off.

2. If it’s raining, leave the sprinklers off.

3. If it’s the right day and it’s dry, turn them on.

STEPS TO DESIGN


If a human being were doing this job, this level of instruction would probably be just fine. With a computer, however, the instructions need more detail. For example, the first instruction, “Every day at 6:00 a.m.,” would have to be expanded more like this:

a. Read the hour.

b. If the hour equals six, go on to the next step.

c. If the hour does not equal six, go back to step a.

Testing the Steps

Now that you have your steps in place, run through each sub-process in your mind to see if anything is missing. Is there an answer for every “if”? Are all the possibilities taken into account?

It may help you to draw out your control process as a flowchart. Often it is easier to see decision points and responses to decisions in a flowchart. You’re still working at the human level at this point; just be aware that the computer may require more details.

Here is a possible flowchart for the simple sprinkler control problem.

:

At 6:00 a.m., read the day of the week

Is it Sunday or Wednesday?

Read the hygrometer

Is humidity less than 100%? Sprinklers off?

Turn sprinklers on and set timer for 15 minutes

Turn sprinklers off

Yes

Yes

Yes

No

No

No

Wait 24 hours

Timer expired?

Yes

Turn sprinklers off

No

Simple Sprinkler System Process Flowchart



Building the StrategyOnce you have the control problem solved in detail, you can begin building the strategy in PAC Control. Now you’ll add all the logical details the computer needs.

Configuring Hardware

The first step in building your strategy is to configure your control engine, I/O units, and I/O points. (For more information and step-by-step procedures, see “5: Working with Control Engines” and “6: Working with I/O.”) You can add more I/O units and points later if needed, but it saves time to configure them now.

When you solved this control problem, some of the inputs and outputs you defined were physical I/O, such as the hygrometer and the switch to turn on the sprinklers. You configure these physical inputs and outputs as the I/O points.

Here are the I/O points you might configure for the simple sprinkler system:

Determining and Configuring Variables

Some of the inputs and outputs you defined when you solved the problem were not physical I/O, but information. For example, the day of the week is not a physical input; it’s a piece of information you can get using a command in PAC Control. These inputs and outputs become variables.

You also need variables to store the information that input points give you. And you may need variables for manipulating information.

To determine the variables you need, think about the pieces of information your process requires. Then look at the PAC Control commands in the PAC Control Command Reference. Find the commands you need and check them to see what types of variables each command requires.

For example, you need to know what day of the week it is. Will the control engine give you this information as a string (for example, “Wednesday”) or in some other format? When you check the command Get Day of Week, you discover that the day is returned as a number(Wednesday = 3), so you set up this variable as a numeric integer.

Physical I/O Type I/O Point Name

Hygrometer Analog Input Hygrometer

Sprinkler status Digital Input Sprinkler_Status

Sprinkler switch Digital Output Sprinkler_Switch

STEPS TO DESIGN


Here are some variables you may need. (See “9: Using Variables and Commands” for more information and step-by-step procedures to add variables.) You can change them or add other variables later if necessary.

Creating PAC Control Charts and Adding Instructions

If you have already drawn the process in a flowchart, this step will go faster. PAC Control is based on flowcharts because they are a natural way to show a control process. And the block names and instructions you add to charts—just like the names of variables—are in normal, everyday language. (For more information and step-by-step procedures, see “8: Working with Flowcharts” and “9: Using Variables and Commands.”)

The difference between the flowchart you drew before and the chart you create in PAC Control is that the flowchart was designed for human beings, but the PAC Control chart must be more detailed so the computer can follow it.

Because the chart is more detailed—and because most control processes are far more complex than our sprinkler system—you will usually create multiple charts for a PAC Control strategy. Break the process down into logical chunks, or modules, and then create a chart for each module. A modular design makes it easier to test and to update your strategy.

Even for a simple process like our sprinkler control, there is no single “correct” way to solve the control problem and build the strategy. Instead, there are many possible ways. The following chart shows one example:

Variable Needed Type Name in PAC Control

Hour of the day Numeric (32-bit integer) Time_of_Day

Day of the week Numeric (32-bit integer) Day_of_the_Week

Humidity Numeric (float) Humidity

Down timer Timer Timer



One difference between this chart and the human-level chart on page 76 is that several delays have been added to the chart. There is one before rechecking the hour of the day, one before rechecking the day of the week, one before rechecking whether the timer has expired, and finally one before starting the flowchart over again.

This sprinkler system is not time-critical. If the sprinklers turn on at a little past 6:00 a.m. or the grass is watered an extra few seconds, it doesn’t matter. Delays give the control engine time to do other things. (For more information on delays and using control engine time effectively, see page 95.)

Each block in the chart contains the PAC Control commands (instructions) that do the work in the system. For example, here are the instructions for the block “Turn on sprinklers, set timer”:

STEPS TO DESIGN


As you create charts and enter instructions, keep referring to the PAC Control Command Reference. The Command Reference describes the “arguments” for each command, which are pieces of information you must enter in the instruction. You can also press F1 to open online help for commands, which gives you the same information as in the printed Command Reference.

For example, one of the commands shown above, Set Down Timer Preset Value, has two arguments. The Command Reference and online help tell you that the first argument—the target value, or the value from which the timer counts down—can be a float variable or a float literal (entered in either decimal or hexadecimal form), and that the second argument is the name of the down timer variable. You need this information when you enter the instruction in the Add Instruction dialog box.

The sample flowchart we’ve shown uses standard PAC Control commands only. If you have a programming background, you may wish to incorporate OptoScript blocks in your flowchart. OptoScript is a procedural language that can simplify some programming tasks, including string handling, math calculations, and complex loops and conditions. See “11: Using OptoScript” for more information.

Compiling and Debugging the Strategy

When all charts are completed and their instructions added, the next step is to compile and debug the strategy. But first, check your hardware. Check cabling and connections, and make sure the actual I/O matches the configured I/O in the strategy.

Now compile and debug the strategy. (See “7: Working with Strategies” for more information and step-by-step procedures. If you have problems, see “A: Troubleshooting.”) If you have multiple charts, debug each one separately and then debug the strategy as a whole. It is easier to find errors in one flowchart than in a group of interrelated ones.

Make sure the connections between charts are accurate. For example, is a chart started at the correct block in another chart?

Use the debugging tools discussed in Chapter 6 to find errors by stepping through a chart and setting breakpoints to discover which block or line contains the problem. And if you’ve tried everything and it still doesn’t work, contact Opto 22 Product Support. (See page 5.)

Arguments



Using and Improving the StrategyAny strategy is one of several possible ways to solve a control problem. One way may be more efficient under some circumstances; another way may be better for others. As you use the strategy over time, as control needs change, and as you become more knowledgeable about PAC Control, you’ll find ways to make the strategy better.

Basic RulesThe sprinkler strategy we just created is a simple example. This section gives basic rules to keep in mind when you’re solving more complex control problems.

When you create a new PAC Control strategy, a Powerup chart is automatically included. You add all the other charts you need, and the total number of charts in the strategy is limited only by the control engine’s memory. Be aware, however, that the maximum number of charts that can be running at any one time is based on the control engine you are using:

• 32 charts on a SNAP PAC S-series controller

• 16 charts on a SNAP PAC R-series controller

Program logic moves through a flowchart in one of two ways: flow-through or loop.

• A chart with flow-through logic performs a set of specific commands and then stops. It has a beginning and an end, and at the end is a condition or action block that has no exit.

Subroutines, the Powerup chart, and any other chart that does not need to run continuously should always have flow-through logic. In complex strategies, be careful when using delays and condition looping (waiting for something to occur) in charts with flow-through logic.

• A chart with loop logic has no end. It loops through a set of actions and conditions continuously. A loop-logic chart can have several paths through which the direction of the logic may flow, depending on certain criteria. Use loop logic for a chart that needs to run continuously. (The simple sprinkler chart has loop logic; it runs continuously.)

Chart GuidelinesAs you design your strategy, put each sub-process of your overall control problem into a separate chart within the strategy. On a SNAP PAC R-series controller, a maximum of 16 charts (plus one host task) can run at once. On a SNAP PAC S-series controller, 32 charts (plus one host task) can run at once. (For more information, see “Optimizing Throughput” on page 95.)

In general, follow these chart guidelines:

BASIC RULES


• Use the Powerup chart just to set initial values for variables, perform setup commands, and start the main charts. Use flow-through logic so the Powerup chart will stop as soon as the other charts begin.

• Create a few charts to monitor essential or time-critical pieces of your process, such as emergency stops on dangerous equipment or I/O that must be monitored continuously. These charts should use loop logic so they are constantly running.

• If a set of operations is used multiple times in your strategy or is used in more than one strategy, you can put that logic in a subroutine and call the subroutine when needed. Calling a subroutine doesn’t require as much time as calling a chart or starting a new chart. In addition, a subroutine starts as soon as it is called in the context of the chart that is calling the subroutine. A Start Chart command is simply placed in the task queue and started in turn. See “12: Using Subroutines” for more information.

• Use the text tool to type a descriptive title in each chart and add any necessary explanations. Keep blocks far enough apart to easily see the flow, and if possible, design the chart so its entire flow can be seen within one window. If a chart becomes too complex, split it into smaller charts.

• When you use OptoScript code, remember that it is not self-documenting. Be sure to add comments so that you or others can easily see what the code is doing. (Similar comments are also useful in other PAC Control flowchart blocks.) Use OptoScript blocks within a flowchart for operations they make easier, such as string handling and math calculations, but keep the logic and purpose of the strategy clear in the flowchart.

• Within a chart, leave Block 0 empty. This makes it easy to insert logic at the beginning of the chart by adding a block between Block 0 and the next block. If a block contains more instructions than can be easily traced and debugged, break it down into two or more sequential blocks. Never place another block in the flowchart before Block 0. Charts always start with Block 0, which cannot be deleted.

Naming ConventionsTo save trouble in the long run, it’s wise to establish naming conventions for charts, blocks, variables, I/O units and points, control engines, subroutines, and so on. If you name these elements in a consistent way from the beginning, it is easier to find them in lists, to see related elements, and to know their functions without opening them.

Since PAC Control automatically alphabetizes these names, you can plan naming schemes to place similar items together in the way you expect to use them.

Names have a maximum length of 50 characters. They can be all upper-case characters, or they can be mixed case.

In chart names, for example, you might include a few letters indicating whether the chart monitors critical tasks, is a master chart calling others, or is periodically called:

• Mntr_Tank_Leak (constantly running chart that monitors a critical situation)

• Mstr_Conveyor_Process (master chart that calls others for a sub-process)



• Call_Message_Display (chart called by a master chart for a specific purpose)

Block names should tell what the block does, so you can understand a chart without needing additional explanations. Block names should describe the purpose of the instructions within them. Use a question for the name of a condition block, with a true exit reflecting the answer yes.

• Read Thermometer (action block)

• Temperature Too High? (condition block)

• Turn On Pump 1 or Pump 1 On (action block)

• Pump On? (condition block)

Variable names can include Hungarian notation to indicate the type of variable, since the variable type is not always apparent in its name. For example a variable named Month might be either a string or an integer. However, using Hungarian notation, sMonth indicates a string, and nMonth to indicates an integer.

Another good practice is to identify variables used in a single chart differently than variables used by more than one chart or process, especially if you have a large chart and want to separate these types of variables. For variables used only in a table you can include the table name in the variable name. For example, you might use the name Fail_Count_in_Config_Values for a variable to be used in a table named Config_Values.

The following table shows suggested notation for use in PAC Control:

In I/O point names, you may want to indicate the point’s function, the state of the device when the point is active, its location, or a schematic reference. You can abbreviate names of familiar devices and write out less familiar names. Include the information you need in the order in which it will be most useful to you:

• Heater_Switch (You have only one heater.)

• Htr6_Switch_SW23B (You have many heaters, and the schematic reference is needed.)

Variable type Letter Variable type Letter

integer 32 variable n pointer variable p

integer 32 variable used as Boolean b pointer table pt

integer 32 table nt digital I/O unit dio

integer 64 variable nn mixed I/O unit mio

integer 64 table nnt analog input point ai

float variable f analog output point ao

float table ft digital input point di

down timer dt digital output point do

up timer ut chart cht

string variable s communication handle cmh

string table st

INSTRUCTION EXAMPLES


• Cnvyr_Speed_Encoder_BldgA (You want all conveyors to appear together.)

• BldgA_Cnvyr_Speed_Encoder (You want all points in Building A to appear together.)

Instruction ExamplesThis section includes examples of common instructions you may want to use. See “10: Programming with Commands” for additional information on programming with PAC Control. If you need to use math calculations, strings, or complex loops and conditions in your strategy, also see “11: Using OptoScript” for examples of OptoScript. OptoScript is a procedural language within PAC Control that can make programming easier, especially if you are an experienced programmer.

Creating Messages to Display On ScreenYou may need to create messages to display on screen, for example to give data to operators. Typically these messages consist of some specific, literal words and symbols followed by a variable value and maybe some additional literal words or symbols.

You can create the message in a single block in your PAC Control chart, like this:



Alternatively, you can create the message by placing the following OptoScript code within a single OptoScript block:FloatToString(Current_Temp, 5, 1, Current_Temp_String);Current_Temp_Message = "Current temperature = " + Current_Temp_String + "F.";

OptoScript can be more efficient for string handling than standard PAC Control commands. See “11: Using OptoScript” for more information.

1. To enter the literal text, use the command Move String. Remember to include spaces where you want them to appear, such as after the equal sign.

2. Add the variable value by converting it to a string and appending it to the string you just created.

3. If needed, append another literal string.



Error HandlingEvery strategy should have a way to handle errors. It’s important to check values and errors that are returned from the commands in your strategy. Communication to an I/O unit, for example, will be automatically disabled if a command sends it variable values that are clearly wrong, such as a memory map address in an incorrect format.

CountingIf an I/O unit supports counting, any digital input on it can be used as a counter. Counters count the number of times the input changes from off to on. You must start the counter before you can read it. See “Counters” on page 284 for more information.

Counters are often started in the Powerup Chart. For example, suppose you wanted to count the number of widgets moving along a conveyor belt from manufacturing to shipping. You could start the counter in the Powerup Chart, like this:

Condition blocks determine whether an event has occurred

Action block clears latches and interrupts

Action blocks take necessary action when event occurs

Add similar logic for additional I/O units as necessary

Condition block determines whether an I/O unit has generated an interrupt



Once the counter is started, you can read its value at any time by using the command Get Counter.

If you want the counter to start over when you read its value—for example, to count the number of widgets in each 24-hour period—use the command Get & Clear Counter.

Using a Count Variable for Repetitive ActionsA numeric variable for counting is useful when the same action needs to be repeated a specific number of times. For example, suppose your process includes filling a packing box with a dozen bags of cookies. You can use a count variable to track how many bags are dropped into the box.

Here’s part of a chart showing how you would use a count variable in this way:

The counter is started in the Powerup Chart.



If you are an experienced programmer, you’ll notice that this example is a for loop. You can use the following OptoScript code within a single OptoScript block to accomplish the same result:for Bag_Count = 1 to 12 step 1 //Count 12 items dropped into box

Bag_Dropper = 1; //Turn on bag droppernext

See “11: Using OptoScript” for more information on using code to streamline control structures in your strategy.

Programming Case StatementsA frequent need in programming is to create case statements, also called “switch” statements, “if/then/else” statements, or “nested if” statements. These statements create multiple decision points: if the condition is A, then X will happen; if the condition is B, then Y will happen, and so on. (This example uses regular PAC Control commands; see “11: Using OptoScript” for another option that takes up less space in your flowchart.)

For example, suppose you have a conveyor with three speeds: high (3), low (2), and stopped (1). Sometimes it runs at high speed, sometimes at low speed; but before a box can be put on the conveyor, the conveyor must be stopped. And it can only be stopped from low speed, not from high speed. Here’s a portion of a chart showing the case statements that control this process:



The example above shows three cases, because there are three possible speeds and each speed demands a different action.

If you had only two possibilities, for example if the box could also be put on the conveyor at low speed, you could handle both possibilities within one condition block. For example, you could put two Equal? commands in the same condition block, and check the Or operator, as shown at right.

Using a TimerTimers come in two forms:

• Up timers count up from zero and are generally used to measure how long something takes.

• Down timers count down to zero from a number you set and are frequently used to determine when events should begin.

Here’s an example of a down timer. This process starts every 1.5 seconds.

Conveyor speed is checked and moved (copied) into a variable.

Each condition block checks for a particular speed. This one checks for high speed (3).

If speed is too high, it is shifted down to the next level, until the conveyor is finally stopped and the box can be put on.

Or operator



Timers can be tricky. For additional details, see “Using Timers” on page 319.

Using a Flag LockThe Flag Lock and Flag Unlock commands allow you to give a task exclusive access to one or more objects—such as tables, integers, or I/O units—until the task is complete. For example, if you want two different charts to change the values in the same table, it is important for one chart to complete its task before allowing the second chart to access the table.

To demonstrate, the following charts show how to construct two charts in a strategy so that each chart can access the same table without interference from the other chart.

Chart 1 and Chart 2 are very similar. The main difference is that one block (D) in Chart 1 adds 2 to each table element, while in Chart 2 it adds 3.

The starting value for the timer is set in Block 0.

When the timer has expired, it is restarted and the process begins.

When the process ends, the logic loops back to check whether the timer has expired again.

The condition block checks whether the timer has reached zero. If it hasn’t, the chart loops until it has.



Here’s what each block accomplishes:

A—Get Table Lock. Uses the following instructions to wait until Chart 2 unlocks the flag before it locks the flag on the table. It also tracks the number of times Chart modifies the table, and it gets the length of the table. The Timeout value of -1 makes the chart wait the other chart has successfully unlocked the flag on the table. See also, “Flag Lock Timeout Values” on page 92.

Using the numeric variables Modified_by_Chart1 and Modified_by_Chart2 (from Chart 2), a watch window can track the number of times the table has been modified by each chart. For more information, see “Using a Watch Window” on page 39.

Chart 1 Chart 2

B

A

C

D

E

B

A

C

D

E

Flag lock will wait until Chart 2 unlocks the flag on the table. See also, “Flag Lock Timeout Values” on page 92.

Tracks the number of times the table has been modified by Chart1

Gets the length of the table and puts it in Int_Table_Index



B—Decrement Table Index. The table has 100 elements, numbered from 0 to 99. This instruction block starts at element 99 and on each loop decrements by 1 to go to the next element. This continues until it reaches index 0.

C—Index >=0. If the index is greater or equal to zero, the chart proceeds to D. If the index equals -1, the chart goes to E.

D—Add 2 (or 3) to Table Element. Adds two (or three) to the value of the current table index.

E—Release Table Lock. This block uses a Force unlock of zero, which means it will only unlock for the chart that locked the flag. In this case, if Chart 1 locked the flag, only Chart 1 can unlock the flag.

Flag Lock Timeout Values

The following chart shows the effect of different Timeout values used with the Flag Lock command:

Pointers and IndexingThe following examples show three possible ways to control 16 fans based on setpoints.

Timeout Effect

-1

Wait until success.The application will wait (block) as long as it takes to lock the flag. Since it never gives up, the only value that can be returned is 0.

0

Don’t wait at all. Succeeds only if the flag is available to be locked immediately. Makes this a non-blocking call. If the flag is not already locked, a return of 0 (Suc-cess) is returned. If the flag is locked, a -17 (Already Locked) error is returned.

Value greater than 0

Wait maximum of value milliseconds to lock the flag. If it succeeds within the specified time, 0 is returned; otherwise, a -37 (Timeout on Lock) error is returned.

Value less than 0 Produces a-8 (Invalid Data) error



Without Pointers

The first way, shown below, uses individual fan outputs and setpoint variables to determine whether to turn off or on the appropriate fan. It’s a simple way to solve the problem but takes a long time to program and produces a large, repetitive section in the flowchart. It also consumes more control engine memory, due to the large number of conditional and action blocks.

Each fan output (Motor01–Motor16) uses a separate temperature input (Temp01–Temp16) and a separate setpoint variable (SP01–SP16). The flowchart cycles through them all to control the fans.



With Pointers and Indexing

The second way uses pointers and indexing to accomplish the same result in a smaller space, using less control engine memory and fewer programming steps. The fan outputs and the temperature inputs are referred to by pointers. The setpoints, instead of requiring individual variables, are simply numbers in a table.

Each fan output (Motor01–Motor16) uses a separate temperature input (Temp01–Temp16) and a separate setpoint variable (SP01–SP16). The flowchart cycles through them all to control the fans.



Using OptoScript

The third way also uses pointers and indexing, but places all the action in an OptoScript block. See “11: Using OptoScript” for more information on using OptoScript.

Optimizing ThroughputFor tips on how to design your PAC Project™ system and program your PAC Control™ strategy to ensure optimum system performance see form 1776, Optimizing PAC Project System Performance.

For additional information, see form 1702, the PAC Display User’s Guide.

The flowchart sets initial values for the pointers, and then cycles through the pointer tables to control the fans. (Tables have already been initialized in the Powerup chart.)

OPTIMIZING THROUGHPUT



5: 5: Working with Control EnginesChapter 5

5: Working with Control Engines

IntroductionThis chapter shows you how to configure and work with control engines. See “Compatible Control Engines and I/O Units” on page 6.

In this ChapterConfiguring Control Engines .....................................................97Using Network Segmenting in PAC Control .................... 101Using Ethernet Link Redundancy in PAC Control.......... 102Using Redundant Controllers................................................. 107Changing or Deleting a Control Engine ............................ 107Inspecting Control Engines and the Queue .................... 109Downloading Files to the Control Engine ........................ 114

Configuring Control Engines Before you can use a control engine to run a strategy, you must first define the control engine on your PC and then associate the control engine with your PAC Control strategy.

• See “Defining a Control Engine on Your PC” below to identify the connection through which the PC and the control engine communicate. Because this process writes to the Windows Registry on your PC, you must define control engines for each computer that uses your strategy. (If your computer can boot to two operating systems, you must configure control engines for each OS.) You can define control engines in PAC Control or in the software utility PAC Terminal.

• See “Associating the Control Engine with Your Strategy” on page 100 to identify which defined control engine is the active control engine. Although you can associate several control engines with the same strategy if necessary, the strategy can be downloaded to only one at a time. The control engine set to receive the download is called the active engine. You must use PAC Control for associating the control engine with your strategy.

CONFIGURING CONTROL ENGINES


Defining a Control Engine on Your PC1. Choose one of the following:

– Using PAC Terminal: Choose Start > Programs > Opto 22 > PAC Project 9.0 > Tools > PAC Terminal. From the Configure menu, choose Control Engines to open the Select Control Engine dialog box. Skip to step 3.

– Using PAC Control: With a strategy open in Configure mode or Online mode, double-click the Control Engines folder on the Strategy Tree.You can also select Configure > Control Engines, or right-click an individual control engine on the Strategy Tree and select Configure.

The Configure Control Engines dialog box appears.

2. Click Add.

The Select Control Engine dialog box appears.

This dialog box lists all the control engines configured on your system, whether or not they are associated with your strategy.

3. If the control engine you want appears in the list, it has already been defined on this PC, click to highlight the control engine’s name and then click OK. Then skip to “Associating the Control Engine with Your Strategy” on page 100.

4. If the control engine you want is not in the list, click Add.

The Control Engine Configuration dialog box appears.

CHAPTER 5: WORKING WITH CONTROL ENGINES


5. Complete the fields as described in “Control Engine Configuration Dialog Box” below.6. Click OK. 7. In the Select Control Engines dialog box, the control engine appears in the list.

8. In the Select Control Engine dialog box, highlight the control engine you want to associate with the strategy. Click OK. Continue with “Associating the Control Engine with Your Strategy” on page 100.

Control Engine Configuration Dialog Box

A—Control Engine Name. Enter a descriptive name for the control engine. Valid characters are letters, numbers, spaces, and most other characters except colons and square brackets. Spaces cannot be used as first or last characters.

B—System Type. Select the system type:

A

B

DEF

C

CONFIGURING CONTROL ENGINES


• Standard: A normal system not using redundant networks or redundant controllers.

• Redundant Networks (PRO only): A system that has redundant networks, which is also referred to as link redundancy. When selected, two IP address boxes are available under Settings for the primary and secondary networks. See “Configuring Ethernet Link Redundancy” on page 5-106 for more information.

• Redundant Controllers (PRO only): Use with a system configured with the SNAP PAC Redundancy Option. When selected, three IP address boxes are available under Settings for Controller 1, Controller 2, and Arbiter. For more information on setting up the Redundancy Option, see form 1831, the SNAP PAC Redundancy Option User’s Guide.

C—Address. The IP address text boxes available depend on your System Type. Each address is entered in decimal notation (for example, 192.9.200.24).

• For Standard: Enter the IP address of the control engine.

• For Redundant Networks (PRO only): Enter the Primary and Secondary IP addresses. The Primary address is ETHERNET 1 on a SNAP PAC controller, and the Secondary IP address is ETHERNET 2. Both IP addresses use the same port number. See “Configuring Ethernet Link Redundancy” on page 5-106 for more information.

• Redundant Controllers (PRO only): For the SNAP PAC Redundancy Option. Enter addresses for Controller 1, Controller 2, and Arbiter. For more information on setting up the Redundancy Option, see form 1831, the SNAP PAC Redundancy Option User’s Guide.

D—Port. Enter the control engine’s IP port number. The default of 22001 is the port of the host task on the control engine; this default normally should not be changed.

E—Retries. Retries indicate the number of times PAC Control will reattempt communications with the control engine. Since retries are automatically handled by the protocol (TCP/IP), enter zero here.

F—Timeout. Enter the timeout value in milliseconds. Timeout value is the length of time PAC Control tries to establish communication through the port. If it fails, it tries again as many times as specified in D. Any positive integer is valid. For Ethernet, 3–5 seconds (3000–5000 milliseconds) is a good starting point.

Associating the Control Engine with Your StrategyAfter you have defined the control engine on your PC (see page 98), it can be associated with your strategy. 1. If you are in PAC Terminal, close PAC Terminal. Open the strategy in PAC Control

(Configure mode or Online mode) and choose Configure > Control Engine.

In the Configure Control Engines dialog box, the engine’s name appears in the list.



2. Check to make sure the correct control engine appears in the Active Engine field. If not, highlight the one you want and click Set Active.

Only one control engine can be active at any time. If only one control engine is listed, it automatically becomes the Active Engine.

Your control engine configuration is complete.

Using Network Segmenting in PAC ControlYou can take advantage of the two independent Ethernet network interfaces on a SNAP PAC controller to segment the control network from the company network. Because the two network interfaces are completely independent and have separate IP addresses, they can be set up on two separate networks. Host traffic can communicate on one, while the controller communicates with the I/O units on the other.

To segment networks, start by assigning a secondary IP address to the controller in PAC Manager, following instructions in the PAC Manager User’s Guide. The secondary IP address is used for communication through the controller’s Ethernet 2 interface. Remember that this interface must be on a completely separate network segment.

You don’t need to do anything special in PAC Control. Configure only one control engine, using the IP address of the Ethernet interface to be used for host communication. The control engine will direct communication to I/O units through the other interface, based upon the I/O unit’s IP address. The IP addresses of the I/O units must be compatible with the secondary IP address of the controller.

NOTE: PAC Display Basic and other hosts on the company network cannot communicate with I/O units when they are on a separate network. To solve this problem, you can purchase PAC Project Professional, or PAC Display Professional and OptoOPCServer (version 7.0 and newer) separately; these applications support network segmenting by communicating with I/O units through the

List of control engines

Active engine

USING ETHERNET LINK REDUNDANCY IN PAC CONTROL


controller. Also, you can add a second network interface card (NIC) and assign it an IP address compatible with the I/O unit network.

Using Ethernet Link Redundancy in PAC Control Ethernet link redundancy provides a backup network connection in case the primary connection route becomes unavailable. If that happens, the controller uses a secondary communication route.

There are two types of link redundancy in PAC Project, which you can use individually or combined:

• Controller to I/O: When link redundancy is configured from the controller to I/O, if communication to the primary I/O unit IP address fails, communication switches automatically to the secondary I/O unit IP address, which usually is the second Ethernet network interface on a SNAP PAC R-series controller. See “Commands for Ethernet Link Redundancy” on page 289 for more information on primary and secondary I/O units.

NOTE: If your system has redundant controllers, in order to use link redundancy from the controller to the I/O, you must connect ETHERNET 2 on the controllers and on the I/O units to the same switch. No other devices can be connected to that switch.

• PAC Display Pro to controller: When a PAC Display Professional project is installed on a PC with two network interface cards (NICs), the project can be configured to use the primary and secondary IP addresses to access data from the PAC Control strategy running on the control engine. One address is always active. If the primary address is unavailable, then the secondary address becomes the active address, and the PAC Display scanner automatically shifts to the secondary address. If the secondary address fails, then the primary address becomes the active address and automatically tries the primary address again. For details, see from 1702, the PAC Display User’s Guide.

SNAP PAC S-series

SNAP PAC R-series



NOTE: If your system has redundant controllers, you cannot use link redundancy between PAC Display Pro and the controller. For more information on using redundant controllers, see from 1831, the SNAP PAC Redundancy Option User’s Guide.

System Architecture for Ethernet Link RedundancyAs shown in the examples below, you can set up your system in several ways to take advantage of the link redundancy capability in PAC Control. For additional information, see the SNAP PAC controllers’ user’s guides. For details on how PAC Display works with link redundancy, see form 1702, the PAC Display User’s Guide.

Example 1: Ethernet Link Redundancy

In this example, the primary concern is that the Ethernet network may need maintenance or may fail, leaving the computer running PAC Display Professional, the computer running the OptoOPCServer (as the PAC Display scanner), the controller, and the I/O units unable to communicate.

The solution is to connect all these devices on two networks; if one network goes down, devices can communicate on the other. Note that each computer has two network interface cards (NICs). I/O units are controlled by the controller. Each I/O unit is connected to its own group of sensors and actuators, but all are connected to the same two networks.

If one network needs maintenance, for example to replace a switch, you can safely shut it down using the Set Target Address commands in PAC Control and options in PAC Display Professional.

SNAP PAC S-series

PC with two NICs running PAC Display Pro

PC with two NICs running OptoOPCServer



Example 2: Ethernet Link, Computer, and Software Redundancy

The second example of link redundancy illustrates concern not only about the stability of the Ethernet network, but also about the computers and the software run on them. Any of these things—the network, a computer, or the OptoOPCServer or PAC Display Professional software running on the computer—may need maintenance or may fail.

The solution here is to provide duplicate computers and software, and connect all devices on two networks. Each computer has two NICs. I/O units are all controlled by the controller. Each I/O unit is connected to its own group of sensors and actuators, but both are connected to the same two networks.

For more information on using Ethernet link redundancy with PAC Display, see form 1702, the PAC Display User’s Guide.

SNAP PAC S-series controller controls all I/O units



PC with two NICs running OptoOPCServer (as PAC Display scanner)

Ethernet switch, network #1


SNAP PAC R-series SNAP PAC R-series

Sensors and actuators, location #1




Example 3: Ethernet Link Redundancy with Serial I/O Units

This third example of link redundancy shows a SNAP PAC S-series controller with serial I/O units. The redundancy is in the Ethernet networks between the controller and computers running PAC Display Professional and OptoOPCServer. This example provides link redundancy for the Ethernet network. Again, note that the computers all have two NICs.


Two PCs, each with two NICs running PAC Display Pro

Two PCs, each with two NICs running OptoOPCServer (as PAC Display scanner)




SNAP PAC R-series

SNAP PAC R-series




Configuring Ethernet Link RedundancyEthernet link redundancy from PAC Display Pro to a control engine is easy to configure. First, make sure the secondary IP address has been assigned to the controller in PAC Manager. Then in PAC Control, just enter both the primary and secondary IP addresses when you configure the control engine (see page 97). Once you have set up link redundancy for the control engine you are using in your PAC Control strategy, it works automatically in PAC Display.







PCs, with two NICs running OptoOPCServer (as PAC Display scanner)





To configure link redundancy from the control engine to I/O units, enter both the primary and secondary IP addresses when you configure the I/O unit (see “Adding an I/O Unit” on page 122).

Using Strategies with Link RedundancyAlthough PAC Display and OptoOPCServer (as the PAC Display Pro scanner) automatically shift to the secondary address when the primary address is not available, the PAC Control debugger does not. In PAC Control, you control which address receives communication, so you know exactly how communication is occurring during debugging. To change between primary and secondary control engine addresses, follow the steps in “Changing the Control Engine that Receives the Downloaded Strategy” on page 108.

Once you have changed the address, when you enter Debug mode, you are communicating through the address you chose. Downloading the strategy to a SNAP PAC controller through one of its Ethernet interfaces replaces any strategy that was downloaded earlier through its other interface.

Using Redundant ControllersThe SNAP PAC Redundancy Option allows you to configure two redundant SNAP-PAC-S controllers that use the same PAC Control strategy. By utilizing sync blocks in the strategy and persistent/redundant variables, critical data is synchronized in both controllers so that the inactive controller can take over at any time and become the active controller. To learn more about the SNAP PAC Redundancy Option and how to set up a strategy using sync blocks and persistent/redundant variables, see form 1831, the SNAP PAC Redundancy Option User’s Guide.

NOTE: If your system has redundant controllers, you cannot use link redundancy between PAC Display Pro and the controller..

Changing or Deleting a Control EngineSee the following topics to change or delete a control engine:

• “Changing a Control Engine’s Definition” (below)

• “Changing the Control Engine that Receives the Downloaded Strategy” on page 108

• “Removing a Control Engine’s Association with a Strategy” on page 109

• “Deleting a Control Engine from Your PC” on page 109

CHANGING OR DELETING A CONTROL ENGINE


Changing a Control Engine’s DefinitionWhenever necessary, you can change a control engine’s definition on your PC—its name, the port the PC uses to communicate with it, or the PC port setup (such as timeouts and retries). These changes can be made either in PAC Control or in the PAC Terminal utility. 1. Choose one of the following:

– In PAC Control: With the strategy open in Configure mode or Online mode, right-click the control engine name on the Strategy Tree and choose Modify from the pop-up menu.

– In PAC Terminal: Choose Start > Programs > Opto 22 > PAC Project 9.0 > Tools > PAC Terminal. From the Configure menu, choose Control Engine.

Select Control Engine dialog box appears.

2. In the Select Control Engine dialog box, click the control engine you want to change and click Modify.

3. Make the necessary changes, following the same steps you would for configuring the control engine initially. (For help, see “Defining a Control Engine on Your PC” on page 98.)

Changing the Control Engine that Receives the Downloaded StrategyYou can configure several control engines for a strategy, but only one at a time can receive the downloaded strategy. The control engine that receives the strategy is called the active engine.

NOTE: In PAC Control Professional, you can also configure a control engine for Ethernet link redundancy (see “Using Ethernet Link Redundancy in PAC Control” on page 102 for more information). In this case, you can also choose whether the primary or secondary IP address will receive the strategy.

To change the control engine that receives the downloaded strategy, follow these steps:1. Make sure the strategy is open and in Configure or Online mode.2. On the Strategy Tree, right-click the name of the control engine you want to set as the

active engine.

If its name does not appear in the Strategy Tree, follow the steps in “Configuring Control Engines” on page 97.

3. From the pop-up menu, choose Set Active.

The active engine moves to the top of the list in the Strategy Tree.

4. If the control engine is configured for Ethernet link redundancy, right-click the name of the control engine on the Strategy Tree again. From the pop-up menu, choose Use Primary IP Address or Use Secondary IP Address.



Removing a Control Engine’s Association with a StrategyIf you no longer want to use a control engine with a strategy, you can remove its association with the strategy. This action does not delete the control engine’s definition on your PC.

CAUTION: Do not delete the control engine from within the Select Control Engine dialog box. Doing so will delete it from the PC as well as the strategy.

1. Make sure the strategy is open in Configure mode or Online mode.2. On the Strategy Tree, right-click the name of the control engine you want to remove.

From the pop-up menu, choose Delete.

The control engine is no longer associated with your strategy.

Deleting a Control Engine from Your PCIf you are sure that a control engine will no longer be used with your PC, you can delete it using the PAC Terminal utility. Deleting the control engine removes its definition only on the PC you are using. 1. Choose Start > Programs > Opto 22 > PAC Project 9.0 > Tools > PAC Terminal. 2. Right-click the name of the control engine in the list.

CAUTION: Make sure you are highlighting the right one. You cannot undo a deletion.

3. From the pop-up menu, choose Delete.

The control engine is no longer defined on the PC.

Inspecting Control Engines and the QueueYou may want to inspect or change control engines while you are running the strategy in Debug mode. See the following topics to view control engine information and the engine’s message queue, either from PAC Control in Debug mode or from the PAC Terminal utility:

• “Inspecting Control Engines in Debug Mode” (below)

• “Viewing the Message Queue” on page 111

• “Inspecting Control Engines from the PAC Terminal Utility” on page 114

Inspecting Control Engines in Debug ModeWith the strategy running in Debug mode, choose Control Engine > Inspect.

You can also double-click the active engine (the first one under the Control Engines folder) on the Strategy Tree, or right-click the control engine and choose Inspect from the pop-up menu.

The Inspecting dialog box opens.

INSPECTING CONTROL ENGINES AND THE QUEUE


Here you see data relating to the control engine. If you are using Ethernet link redundancy in PAC Control Professional, remember that the information shown is for the IP address you chose before entering Debug mode. (See “Using Strategies with Link Redundancy” on page 107 for more information.)

A—Control Engine. Type of device the control engine is running on and the device’s IP address.

B—Firmware Version. Version number of the firmware (kernel) loaded on the device, and the date the firmware was released

C—Memory Available. Amount of memory (RAM) available on the control engine. For example, a SNAP R-series controller has a total of 16 MB of RAM on the control side, 2 MB of which is battery-backed. Volatile RAM shows the amount of total RAM available for use. Battery-backed RAM shows the amount available in battery-backed RAM, where persistent variables, variables initialized on download, the autorun flag, and the strategy archive are stored. File Storage RAM shows the space available in the control engine’s file system See the PAC Manager User’s Guide for more information about the file system. See also form 1646, the SNAP PAC Memory Usage Technical Note.

D—Up Time. Total time that the control engine has been running since powerup

AB

GE

M

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N

O

L

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JI

Q



E—Device Time. Current date and time recorded on the control engine

F—Sync time to PC. Click to synchronize the control engine’s time and date to that of the PC running PAC Control.

G—Message Queue. Number of messages (information, warning, and error messages) encountered when attempting to run the strategy on the control engine (up to a maximum of 1000 messages). (See “Viewing the Message Queue” below.) Click to open the View Messages dialog box, listing the details of any information, warning, or error messages.

H—Active. Name of the strategy currently running on the control engine, the date and time it was downloaded, and the number of charts currently running.

I—Archive. Information about the strategy currently archived on the control engine

J—Run/Stop. Start or stop the active strategy.

K—Store to Flash. Click to store either the active or alternate strategy to flash memory. Only one strategy at a time can be stored in flash memory. This button is enabled if there is a strategy strored in RAM, even if the strategy is currently stored in flash. See Burned in flash (N) on this dialog box.

L—Alternate. Name of the alternate strategy, and the date and time it was downloaded

M—Switch and Run/Switch. Click Switch and Run to make the alternate strategy the active strategy and run it in the control engine. Click Switch to make the alternate strategy the active strategy without running it.

N—Stored in flash. Shows whether a strategy is currently stored in flash memory.

O—Autorun. Click to indicate whether the strategy should automatically run when the control engine is restarted. The strategy must be stored to flash to autorun. See Store to Flash above“Saving a Strategy to Flash” on page 173.

P—Loop Time. Time required to gather the inspection data from the control engine (the average time taken for a single transaction)

Q—Comm Errors. Any communication errors

Viewing the Message QueueThe message queue holds error, information, and warning messages. All may be helpful in troubleshooting. When a message is placed in the queue, a blue INFO, yellow WARNING, or red ERROR box appears in the PAC Control status bar, as shown in the following diagram.

INSPECTING CONTROL ENGINES AND THE QUEUE


To see the message queue, 1. Click the INFO, WARNING, or ERROR box.

2. To see all the information in the column, drag the edge of a column heading. See “Message Queue Information” below.

3. To see all of the information for one message, double-click the message.

Messages have been placed in the queue.



4. To refresh the display with the latest messages, click Refresh.5. To copy all messages in table format for transfer to another program such as Excel, click

Copy All.6. To delete the top (oldest) message on the list, click Pop Top Message.7. To delete all messages, click Clear Messages.8. Close the dialog box to return to the Inspect Control Engine dialog box.

Any changes you have made to the queue are reflected there.

Message Queue Information

Each message in the View Messages dialog box includes the following information:

Code. The message or error code number (see “List of Common Messages” on page 382) or User if the message was placed in the queue using the command Add Message to Queue.

Severity. Information, Warning, or Error.

Chart and Block. The chart and block being executed when the error occurred. If the error occurred someplace outside the strategy, for example when trying to connect to an I/O unit, Chart shows <system>. If the error occurred in a subroutine, Chart shows the chart that called the subroutine, and Block indicates the name of the subroutine plus the block number in the format <sub name>.<block number>. For example, error #4 above (“Cannot divide by zero”) occurred in block 1 of the subroutine Variable_Increase_Notification, which was called by the Temperature_Control chart.

Line. If you are in Full Debug mode, the line being executed when the error occurred.

Object. The table, I/O unit, or other object affected by the message. In errors #1 and #2 above, the control engine was unable to communicate with I/O unit EIO_C. The unit’s IP address is shown for easy reference.

DOWNLOADING FILES TO THE CONTROL ENGINE


Time and Date. When the error occurred.

Inspecting Control Engines from the PAC Terminal UtilityYou can also inspect control engines from the PAC Terminal utility.1. Click the Windows Start menu and select Programs > Opto22 > PAC Project 9.0 > Tools

> PAC Terminal.

The PAC Terminal window appears.

2. Double-click the control engine you want to see (or right-click it and choose Status from the pop-up menu).

The Inspect Control Engine dialog box appears. The dialog box is explained on page 109.

Downloading Files to the Control EngineThis section discusses how to archive strategies and download Forth files directly related to a strategy, such as library or initialization files. For information on using the brain’s file system to store data and manipulate it within your strategy, see page 269.



Archiving StrategiesArchiving strategies on the control engine provides a backup in case original strategy files on the computer are lost. Archive files are date and time stamped, and zipped for compact storage. The archive file name on the control engine is in one of the following formats:

Path\Filename.Download.D02282000.T114351.zipPath\Filename.Online.D02282000.T114351.zip

The date stamp (D) is in the format mm/dd/yyyy. In the examples above, the date is February 28, 2000. The time stamp (T) is in the format hh/mm/ss. In the examples above, the time is 51 seconds past 11:43 A.M.

Archiving to the Control Engine

When you archive a strategy to the control engine, you are placing the zipped file in battery-backed RAM. If power to the control engine is lost, the archive is still there. Archiving to the control engine as well as the computer makes sure that an older strategy can always be found and updated, even after personnel changes occur and years pass.

Make sure the control engine has sufficient memory available to store the archive file. Since only one strategy can be on the control engine at any time, only the latest archive for that strategy is on the control engine. Other archives are erased during strategy download.

Follow these instructions to archive a strategy to the control engine:1. In PAC Control, choose File > Strategy Options.

2. On the Archive tab in the Strategy Options dialog box, select “Archive strategy to disk when strategy is downloaded.” Also select “During download, save archive to the control engine and save strategy to flash memory.”



3. Click OK.

The strategy will be archived to the computer and to the control engine when it is downloaded. Any archive already on the control engine will be replaced by the new archive. In addition, the strategy will be saved to flash memory, so it will still be available if power to the controller is turned off.

Restoring Archived Strategies from the Control Engine

If original strategy files are lost or damaged, you can use PAC Terminal to restore the strategy archive from the control engine to a computer. 1. Click the Windows Start menu and choose Programs > Opto22 > PAC Project 9.0 >

Tools > PAC Terminal.




2. Right-click the control engine and choose Upload > Strategy Archive from the pop-up menu.

3. In the Save PAC Control Strategy Archive As dialog box, navigate to the folder where you want to save the archive file. Keep the file name as it is, so you can see the date and time it was originally downloaded to the control engine. Click Save.

A dialog box shows progress as the archive file is uploaded to the computer.

4. Navigate to the zipped archive file. Assuming you are using WinZip, double-click the file name. Highlight all files and click Extract. Extract them to the location you want.

5. When all files are extracted, double-click the .idb file to open the strategy. If necessary, re-link subroutines and files run before or after a strategy.

Re-linking may be necessary because the directory structure in the zip file may not match what was originally on the computer. The zip file structure is as follows:

Root (.idb, chart files, .inf )SubroutinesControl engine files

Control_Engine_Name_1Before run fileAfter run file

Control_Engine_Name_2Etc.



Downloading Files Without Opening PAC ControlUsing the PAC Terminal utility, you can download PAC Control strategies or Forth files related to the strategy, such as library or initialization files, directly to a control engine, without having to open each program.

(For information on using the brain’s file system to store data and manipulate it within your strategy, see “Using the Control Engine’s File System” on page 269.)

NOTE: If you are downloading a PAC Control strategy that requires other files, be sure to download the files in the correct order (for example, library file, then strategy file, then initialization file). If you need to set initial values for individual table elements on strategy download only, see “Setting Initial Values in Variables and Tables During Strategy Download” on page 238.

1. Click the Windows Start menu and choose Programs > Opto22 > PAC Project 9.0 > Tools > PAC Terminal.


2. Right-click the control engine and choose Download > Forth Files from the pop-up menu.

3. In the Download File dialog box, click Browse. 4. In the Open dialog box, locate the file you want to download. When the full path

appears, click OK.

If necessary to find the file, choose All Files from the Files of Type drop-down menu.

The download begins, and a dialog box shows its progress.


6: 6: Working with I/OChapter 6

6: Working with I/O

IntroductionIn addition to configuring a control engine to run your strategy, you also need to configure input/output hardware to do the work: turning things on, setting temperatures, monitoring controls, and so on.

This chapter shows you how to configure and work with I/O units, I/O points, and PID loops.

In this ChapterChoosing a Configuration Tool . . . . . . . . . . . 119Adding an I/O Unit . . . . . . . . . . . . . . . . . . . . . . 122Adding I/O Points . . . . . . . . . . . . . . . . . . . . . . . 128Configuring a Serial Module . . . . . . . . . . . . . 137Changing Point Configuration . . . . . . . . . . . 137Configuring PID Loops . . . . . . . . . . . . . . . . . . 141Inspecting I/O in Debug Mode. . . . . . . . . . . 148Inspecting and Tuning PID Loops . . . . . . . . 153Using Watch Windows for Monitoring. . . . 165

Choosing a Configuration ToolConfiguring I/O is one of your major planning steps in developing a PAC Control strategy. Generally it’s best to configure all I/O units, points, and PID loops at once, before you start building flowcharts.

There are two tools you can use for configuration: PAC Control and PAC Manager. These two tools serve different purposes, but they overlap when it comes to configuring I/O. The graphic on the next page compares their functions.

CHOOSING A CONFIGURATION TOOL


I/O units and points must be configured to match the PAC Control strategy you will run. You can configure most I/O units and point functions either in PAC Control or in PAC Manager.

For most I/O units, if you are already in PAC Control, configuration is easier there and you can use the loopback IP address for I/O units controlling themselves. However, some functions for I/O units cannot be configured in PAC Control.

If you use PAC Manager, you can save your configuration to a file, load it to multiple I/O units at once, and use it for referencing points in OPC. However, you cannot use the loopback address in PAC Manager.

Choose your configuration tool based on what you need to do:

Whichever tool you use for configuring I/O, be aware of the impact if you later change configuration. For example, if you configure I/O in PAC Manager, download the configuration file to I/O units, and then later add a point in PAC Control, remember that your configuration file doesn’t contain that point.

If you use PAC Manager, follow instructions in Opto 22 form 1704, the PAC Manager User’s Guide. When you have finished configuration and saved the configuration file, you can import it into PAC Control following the steps in “Importing I/O Configuration into PAC Control” below.

If you use PAC Control, follow the steps beginning with “Adding an I/O Unit” on page 122.

Use PAC Control for I/O configuration if Use PAC Manager for I/O configuration if

• You have only one I/O unit or I/O unit configurations are different.

• The strategy will run on I/O units that are controlling themselves using the loopback IP address, 127.0.0.1

• You are using an Ethernet network for communications (or using a SNAP PAC controller with an SB brain).

• The strategy handles all logic; you are not also configuring events and reactions on I/O units.

• You have multiple I/O units whose configurations are exactly the same or similar.

• You are using a modem connection (PPP) or SNMP.

• You are using event messages or email.• You are configuring events and reactions on the

I/O unit in addition to strategy logic.• You are not using PAC Control.

PAC Manager TasksPAC Control Tasks

Assign and change IP address

Load firmwareConfigure communications

and events

Configure control engine(So PC running PAC Control can communicate with the SNAP controller)

Program and debug control logic

I/O can be configured in PAC Control. Ethernet-based I/O can also be configured in PAC Manager and imported into PAC Control.

Configure I/O

CHAPTER 6: WORKING WITH I/O


Importing I/O Configuration into PAC ControlIf you have configured all I/O units, points, and PID loops in PAC Manager, follow these steps to import the configuration file into a PAC Control strategy.1. Open the strategy in PAC Control. In the Strategy Tree, right-click the I/O units folder.

From the pop-up menu, choose Import.

2. Navigate to the configuration file you created and saved in PAC Manager. Double-click it to open it.

The configuration information is imported. You can expand the I/O units folder to see the imported units and their points.

If you need to configure additional I/O units from within PAC Control, see “Adding an I/O Unit” on page 122. To tune PID loops, see “Inspecting and Tuning PID Loops” on page 153.

Copying I/O ConfigurationsIf you have two strategies that use similar I/O units and points, you can export an I/O configuration from one strategy into a file, and then import it into the other strategy.

If you need similar configurations for several I/O units, you can use PAC Manager to send it to multiple I/O units at once. (You cannot use PAC Manager for serial-based I/O units.) For more information on using PAC Manager, see Opto 22 form 1704, the PAC Manager User’s Guide.

Creating the Configuration Export File

1. Open the strategy you are copying from in PAC Control. In the Strategy Tree, right-click the I/O Units folder and choose Export from the pop-up menu.

The Export I/O Units to an Opto Tag Database dialog box appears.

2. Navigate to the location where you want to place the export file. Type the file name, and click Save.

ADDING AN I/O UNIT


The export file is created. It is a comma-delimited ASCII file. If you wish, you can open it in Notepad or Excel.

Importing the Configuration File

When you import the I/O configuration file, it does not delete any I/O units or points that are already there. If the import file contains I/O units with the same names as those already in the strategy, you can choose whether to update them. Updating changes points that have the same name and adds new points, but does not delete points.1. Open the strategy into which you want to import the I/O configuration. 2. In the Strategy Tree, right-click I/O Units and choose Import from the pop-up menu.3. Navigate to the location of the export file you created. Highlight its name and click

Open.

The I/O units and points are updated from the configuration file. To see them, click the plus sign next to the I/O Units folder on the Strategy Tree.

Adding an I/O UnitIn PAC Control, the term I/O unit usually refers to a mounting rack with a brain or brain board and up to 16 I/O modules attached.

NOTE: If you have already configured I/O in PAC Manager, you can also add I/O units or points if necessary from within PAC Control, as you add commands to the blocks in your strategy.

1. Make sure the strategy is open and in Configure mode. On the Strategy Tree, double-click the I/O Units folder.

You can also select Configure > I/O.

The Configure I/O Units dialog box opens, showing all configured I/O units.

2. To configure a new I/O unit, click Add or double-click anywhere in the box below any listed units.



The Add I/O Unit dialog box appears.

3. Complete the fields as described in “Add I/O Unit Dialog Box” below.

Add I/O Unit Dialog Box

Use this dialog box to add a new I/O unit to the strategy or edit an existing unit.

For information on saving the I/O Unit Configuration, see “Inspecting I/O Units and Saving Settings to Flash” on page 148.

A—Name. Enter a name for the I/O unit. The name must start with a letter and may contain letters, numbers, and underscores. (Spaces are converted to underscores.)

B—Description. (Optional) Enter a description of the unit.

C—Type. When adding an I/O unit, select the type of I/O unit from the drop-down list. Brain model numbers are listed in parentheses to help you determine which type to choose. When upgrading an older I/O unit to a SNAP PAC brain, possible upgrades are available in the drop-down list.

D—Primary Address. For Ethernet I/O units, type the IP address of the brain attached to the I/O unit. If the unit is local (the same SNAP PAC brain on which the strategy will run), select Local (loopback). This sets the address to a loopback address, 127.0.0.1. This tells the brain to talk to itself, so if you change the brain’s IP address, you don’t have to change the address for the I/O unit.

AB

C

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ADDING AN I/O UNIT


For serial units, type the unit’s address (valid range is 0–255).

E—Secondary Address. (Optional—PAC Control Professional only—Ethernet-based I/O units only) To designate a secondary I/O unit for communication if this I/O unit is unavailable, enter the secondary unit’s IP address. Note that both I/O units use the same port number.

F—Port. For Ethernet-based I/O units, communication with the control engine is Ethernet, and the default port number is 2001. If you have changed this port for security purposes, also change it here. (See the controller’s user guide for details.)

For serial-based I/O units, the communication port and parameters are shown for you. The Serial Address drop-down menu shows which addresses are currently being used. The port must be configured on the Strategy Options dialog box. Also, binary/CRC settings on your hardware are required. For more information, see “Changing the Baud Rate for Serial I/O Units”

G—Enable Communications. Select whether you want communication to the I/O unit enabled or disabled on startup. Enabled is the default. Disabling communication to an I/O unit is the same as disabling communication to all points on the unit.

H—Timeout. Enter the number of times the control engine should try to communicate with the I/O unit, and enter the length of time the control engine should wait for a response when communicating with this I/O unit. If after the first communication attempt there is no response within the timeout period, the control engine retransmits. If there is no response within the timeout period, it transmits again. This repeats according to the number of tries specified. If no response is received within the final timeout period, communication to the I/O unit is disabled. The default number of tries is 3. The default timeout period is 1 second.

In most cases, it is a good idea to start with the default values and only make changes if your system has problems using the defaults.

CAUTION: If the timeout is long and the I/O unit is turned off or unreachable, the control engine could take quite a while to execute a command that talks to I/O. See also, “Tuning the I/O Unit Timeout Value for Ethernet I/O Units” on page 127.

I—Fahrenheit/Celsius. (Analog and Mixed units only) Choose whether temperatures will be handled in Fahrenheit or Celsius.

J—Watchdog. Select whether you want a Watchdog on the unit (not available on remote simple I/O units). The default is No (disabled). If you select Yes, a new field appears; enter the Watchdog timeout value (in seconds). The default timeout is 0.5 seconds.

With a Watchdog, the I/O unit monitors activity on the port. If no communication is received for the specified interval, the unit assumes a Watchdog state. All selected outputs will then immediately go to a specified value, as configured in the Watchdog field of the Add Analog Point or Add Digital Point dialog boxes. (See “Adding I/O Points” on page 128.)



K—Maximum Analog and High-Density Digital Scantime. (Ethernet-based I/O units only) You can decrease the analog and high-density digital scan time to make sure the scanner isn’t slowed or stopped by heavy communication on the network. The Default is 1000 msec. This feature is also available in PAC Manager where you can fine tune the scan time on the fly.

NOTE: Digital Scantime applies only to non-PAC I/O units. PAC I/O units use Digital Feature Resolution Value instead.

See form 1704, the PAC Manager User’s Guide. For more information on optimizing scanner performance, see “Optimizing Throughput” on page 95 in this guide.

Changing the Baud Rate for Serial I/O UnitsNOTE: This section is for PAC Control Basic users. If you have the Pro version, see “Changing the Baud Rate and Mode for Serial I/O Units” on page 126.

If the default baud rate shown in the Add I/O Unit dialog box not correct, you can change it. This baud rate is for communication through the RS-485 port to serial I/O units. It does not affect other serial ports on the controller or communication handles using these ports.

NOTE: Once you have configured a serial port for use with an I/O unit, do not configure a communication handle on the same port.

1. Make sure the strategy is open and in Configure mode.2. Choose File > Strategy Options, then click the Serial I/O Ports tab.

3. Select the correct port for the controller, and then choose the correct baud rate from the drop-down list and click OK.

ADDING AN I/O UNIT


NOTE: If you are configuring a SNAP-PAC-S1 controller you must use port 2. If you are using a SNAP-PAC-S2, see Opto 22 form 1704, the PAC Manager User’s Guide, for the default serial port assignments or to change a serial port assignment.

Changing the Baud Rate and Mode for Serial I/O UnitsThis section is for PAC Control Professional users. If you have the Basic version, see “Changing the Baud Rate for Serial I/O Units” on page 125.

NOTE: Once you have configured a serial port for use with an I/O unit, do not configure a communication handle on the same port.

If the default baud rate shown in the Add I/O Unit dialog box is not correct, you can change it. This baud rate is for communication through the RS-485 port to serial I/O units. It does not affect other serial ports on the controller or communication handles using these ports.

In addition you can also choose Binary or ASCII mode. The controller will talk to all I/O units on that port in the same mode.

NOTE: There is no ASCII version of OptoMMP protocol (which is used on SNAP PAC SB brains), so if a port is set to ASCII, you won't be able to mix mistic and SNAP PAC SB brains as you can in Binary mode.

1. Make sure the strategy is open and in Configure mode.2. Choose File > Strategy Options, then click the Serial I/O Ports tab.

3. Select the correct ports for the controller, and then choose the correct baud rate and mode from the drop-down lists and click OK.



If you are configuring a SNAP-PAC-S1 controller, you must use port 2 for serial I/O units. If you are using a SNAP-PAC-S2, see Opto 22 form 1704, the PAC Manager User’s Guide for the default serial port assignments or to change a serial port assignment.

In addition, make sure to jumper the non-SNAP PAC brain for the correct setting, either Binary CRC (cyclic redundancy check) or ASCII CRC. Although at the brain level you can choose Binary/ASCII and CRC/Checksum independently, the Opto 22 drivers only support binary CRC or ASCII CRC.

ASCII CRC is only for mistic brains. If a port is set for ASCII but has a SNAP-PAC-SB1/2 on it, the compiler will generate a warning.

Tuning the I/O Unit Timeout Value for Ethernet I/O UnitsThe default I/O Unit timeout value is 1 second. However, for best overall performance you can tune the value for your system.

A SNAP PAC controller automatically retries 2 times before disabling communication to an I/O unit that is unresponsive, and it uses the same timeout value for the first attempt and the 2 retries. So, with a 1 second timeout value and 2 retries, it takes 3 seconds before an unresponsive unit is taken offline. This means the chart or command that is trying to read or write to that I/O unit will be delayed by 3 seconds.

When using SNAP PAC Ethernet brains (SNAP-PAC-R1, R2, EB1, or EB2) on a wired LAN (local area network), a timeout value of 0.1 seconds may be fine. When using a WAN (wide area network), a wireless network, the Internet, or you are not sure what the networking technology is, it may be best to use the default value of 1 second. However, if the controller's message queue shows loss of communication with Ethernet I/O units, it may be necessary to increase the timeout value.

For Advanced Users:

If you are an advanced user with a lot of Ethernet experience, you may want to determine normal response times from a brain using an Ethernet capture utility such as WireShark® (www.wireshark.org). Look for the fastest response time, the normal or typical response time, and the longest response time.

Adjust the timeout value to be larger than the maximum observed response time. It is best not to use a timeout value that is too short because this will cause unnecessary communication retries and timeouts. We recommend making the timeout be at least 50% to 100% longer than the maximum observed response time. In addition, we recommend not using a timeout value that is less than 0.1 seconds. For example, if the value is 0.1 seconds, then communication to an unresponsive I/O unit will be disabled within 0.3 seconds. If the network connectivity is very slow, you may need to use a significantly longer timeout value such as 3 to 5 seconds or longer.

ADDING I/O POINTS


Changing Configured I/O Units1. To change a configured I/O unit, make sure the strategy is open and in Configure

mode. 2. Find the I/O unit’s name on the Strategy Tree. Double-click it to open the Edit I/O Unit

dialog box. See “Add I/O Unit Dialog Box” on page 123.3. Make the necessary changes and click OK.

You can also change an I/O unit from the Configure I/O Units dialog box by double-clicking the unit’s name or highlighting it and clicking Modify.

Deleting Configured I/O UnitsYou cannot delete an I/O unit if it has I/O points configured or if the I/O unit is referenced in a PAC Control command.

CAUTION: Be careful when deleting I/O units. You cannot undo a deletion.

1. To delete a configured I/O unit, make sure the strategy is open and in Configure mode. 2. Find the I/O unit’s name on the Strategy Tree. Right-click it and choose Delete from the

pop-up menu.

The I/O unit is deleted from the strategy.

You can also delete an I/O unit from the Configure I/O Units dialog box by highlighting the unit’s name and clicking Delete.

Adding I/O PointsBefore you add an individual I/O point, such as a sensor or a switch, you must add the I/O unit the point is on. See “Adding an I/O Unit” on page 122.

Adding a Digital I/O Point 1. With the strategy open and in Configure mode, double-click the I/O Units folder (not

the individual unit’s icon) on the Strategy Tree.

The Configure I/O Units dialog box appears.



2. Highlight the I/O unit the points are on, and click I/O Points.

The Configure I/O Points dialog box appears.

3. (Pro only) If you are using a non-SNAP I/O unit (not including the B3000), double-click the channel you want to use. Skip to step 10.

4. If you are using a SNAP I/O unit (including the B3000), notice the module icons in the dialog box.

NOTE: This example shows a SNAP PAC I/O unit, so both digital and analog modules can be configured on the same rack.

5. Highlight the number that represents the module’s position on the rack, then click Add.

A list of available modules appears.

Module icons

ADDING I/O POINTS


6. In the Add Module dialog box, choose the module type and then the exact module from the lists.

7. If you want to add points automatically, select “Automatically create points within the new module.”

Use the “Name format” text field to create a format for the point names. Enter any combination of text and the following format codes:

%1 = point type (for example, ai or do)

%2 = I/O unit name

%3 = module position

%4 = channel position

%5 = a unique identifier that is generated automatically

Example: %1_%2_%3%4 would expand to something like di_MyIoUnit_0801.

Example: %1ABC_%5 would expand to something like aoABC_473

8. Click OK.9. In the Configure I/O Points dialog box, click the plus sign next to the new module to

expand it.

Notice that the module icon is color-coded to reflect the type of module being configured: white for digital DC input, red for digital DC output, yellow for digital AC input, and black for digital AC output.



10. Highlight the point you want to configure and click Add.11. Complete the fields as described in “Add Digital Point Dialog Box” below.12. When you have completed the fields, click OK.

The new point appears in the list. Here is an example of how it might look on a SNAP I/O unit:

NOTE: If you need to add several similar points, see “Copying a Configured I/O Point” on page 138.

Module icon

Expand or collapse points on the module by clicking the + or - sign in the box.

Points

ADDING I/O POINTS


Add Digital Point Dialog Box

A—Name. Enter a name for the point. The name must start with a letter and may contain letters, numbers, and underscores. (Spaces are converted to underscores.)

B—Description. (Optional) Enter a description of the point.

C—Type/Module. For non-SNAP I/O units, choose the module type and the exact module from the drop-down lists.

For SNAP I/O units: Type and module are already filled in for you, as shown in the example above.

D—Features. To use a feature of the module, choose it from the drop-down list. You can configure some input modules with a counter, totalizer, or other feature. (Inputs automatically have both on-latches and off-latches.)

E—Default. To set a default state for the point when the strategy is run, click Yes and choose the state (Off or On). To leave the point in the state it was before, click No.

F—Watchdog. (Output modules only) To set a Watchdog, click Yes and choose On or Off from the drop-down list.

G—Enable Communication. Select whether you want communication to this I/O point enabled or disabled on startup. Enabled is the default.

Adding an Analog I/O Point 1. With the strategy open and in Configure mode, double-click the I/O Units folder (not


A

C

D

E

B

F

G



2. In the Configure I/O Units dialog box, highlight the I/O unit the points are on, and click I/O Points.

The Configure I/O Points dialog box appears.

3. (Pro only) If you are using a non-SNAP I/O unit (not including the B3000), double-click the channel you want to use. Skip to step 8.

4. If you are using a SNAP I/O unit (including the B3000), notice the module icons in the Configure I/O Points dialog box.

NOTE: In this example, a digital module has already been added in position zero. This example shows a SNAP PAC I/O unit, so both digital and analog modules can be configured on the same rack.

5. Highlight the number of the analog module’s position on the rack, then click Add.

ADDING I/O POINTS


6. In the Add Module dialog box, choose the module type and then the exact module from the lists. Click OK.

7. If you want to add points automatically, select “Automatically create points within the new module.”

Use the “Name format” text field to create a format for the point names. Enter any combination of text and the following format codes:

%1 = point type (for example, ai or do)

%2 = I/O unit name

%3 = module position

%4 = channel position

%5 = a unique identifier that is generated automatically

Example: %1_%2_%3%4 would expand to something like di_MyIoUnit_0801.

Example: %1ABC_%5 would expand to something like aoABC_473

8. In the Configure I/O Points dialog box, click the plus sign next to the new module to expand it. Notice that the module icon is color-coded to reflect the type of module being configured: blue for analog input, green for analog output.



9. Highlight the point you want to configure and click Add.10. Complete the fields as described in “Add Analog Point Dialog Box” below.11. When you have completed the fields, click OK.

The new point is added.

NOTE: If you need to add several similar points, see “Copying a Configured I/O Point” on page 138.

Add Analog Point Dialog Box

Module icon

Expand or collapse points on the module by clicking the + or - sign in the box.

Points

B

F

G

C

H

I

A

D

E

ADDING I/O POINTS


A—Name. Enter a name for the point. The name must start with a letter and may contain letters, numbers, and underscores. (Spaces are converted to underscores.)

B—Description. (Optional) Enter a description of the point.

C—Type/Module. For non-SNAP I/O units, choose the module type and the exact module from the drop-down lists.

For SNAP I/O units: Type and module are already filled in for you. You may be able to choose a different range or a scalable module from the drop-down list.

D—Full Range. Full range and units for this module. If the module is scalable, use F to change scale.

E—Clamping. (Outputs only—optional) Enter upper and lower clamp if necessary to limit output to the device attached to the point. If fields are left empty, no clamp is applied. To empty the fields, click Clear.

F—Scaling. (Scalable modules only—optional) Use to assign custom units and values to the module. For example, you could scale the readings of a -10 to +10 VDC input point to measure its input as zero liters per second when the real-world reading is zero VDC, and 1000 liters per second when the real-world reading is 5 VDC. This example would look like this:

Custom scaled values can be any floating point value as long as the upper value is higher than the lower value. Note that inputs typically have under-range and over-range capability, which means you can specify a lower or upper value beyond the standard value. Outputs do not have under-range or over-range capability.

To return the units and upper/lower values to the defaults for the module, click Default.

In this example, units are changed to liters/second and lower and upper values are changed. Although the module has an output of -10 to +10 volts, the device attached to the point outputs only 0–5 volts. Scaling reflects the device’s range.In this case Clamping protects the device by ensuring that out-of-range voltage will never be sent to it.



G—Default. To set the initial values for this I/O point when the strategy is run, click Yes and define the value. To leave the internal/external values at their last state, click No.

If communication to the point is disabled, only the internal values (IVALs) are updated by the control engine. The real-world external values (XVALs) for inputs don’t change because they are controlled by external devices. The IVALs for inputs are set and will be overwritten by the XVALs unless communication to the point is disabled.

H—Watchdog. (Outputs only) To set a Watchdog on this point, click Yes, and define the value to be assigned to the output if the Watchdog is triggered. A Watchdog is triggered if no communication activity is detected on the bus for the amount of time specified in the Watchdog field of this point’s I/O unit. For no Watchdog, click No.

I—Enable. Select whether you want communication to this I/O point enabled or disabled on startup. Enabled is the default.

Configuring a Serial ModuleUse PAC Manager to configure SNAP serial communication modules, including the Profibus module. See the PAC Manager User’s Guide (Opto 22 form 1704) for instructions.

Changing Point Configuration

Moving a Configured I/O PointYou can move most configured I/O points to an empty point on the same I/O unit or on a different unit. 1. With the strategy open in Configure mode, double-click the I/O Units folder on the

Strategy Tree.2. In the Configure I/O Unit dialog box, highlight the unit the point is on and click I/O

Points.

The Configure I/O Points dialog box opens. For a SNAP I/O unit, it looks something like this:

CHANGING POINT CONFIGURATION


3. If necessary, expand an individual module by clicking its plus sign , or expand all of the modules by clicking Expand All.

4. Highlight the point you want to move and click Move To.

5. In the Select a target channel area of the Move Point To dialog box, highlight the location you are moving the point to. Then click OK.

You return to the Configure I/O Points dialog box, and the point has been moved.

Copying a Configured I/O PointIf you have several points that are the same, you can copy a configured point:

• To fill empty points on the same module.

• To fill all empty points on the I/O unit.

• To another other point on the same or a different I/O unit.1. With the strategy open in Configure mode, double-click the I/O Units folder on the

Strategy Tree to open the Configure I/O Points dialog box.



2. Click Expand All so you can see the points.

3. Highlight the point you want to copy and click the Copy To button. From the pop-up menu, choose one of the following:

To copy the point to fill empty points on the module, choose Fill In Module.

The point is copied to the other empty points on the same module.

To copy the point to fill all empty points on the I/O unit, choose Fill In I/O Unit.

The point is copied to all empty points on similar modules (for example, to all empty points on digital input modules, whether they are the same or a different part number) and to all compatible slots without configured modules.

Original point

Copied points

CHANGING POINT CONFIGURATION


To copy the point to one other point, either on the same or a different I/O unit, choose To Specific.

The Copy To dialog box opens.

In the left column, choose the same or another I/O unit. In the right column, choose the location of the point to copy to.

Available points are shown in black. Already configured points, points on a different type of module (digital output instead of digital input, for example), and point numbers not on the rack (such as point 40 on an 8-module rack) are grayed out.

If the point is copied to an empty module slot, the module part number from the copied point is added, too.

This module was already configured. The copied point filled in all empty points, even though the module is a different part number.

No module existed in this slot. Both the points and the module were copied from the original.



4. After you copy a point, change the new point as needed by double-clicking its point name. In the Edit Digital Point dialog box, type the new name and make any other changes.

Changing a Configured I/O Point1. With the strategy open in Configure mode, expand the I/O Units folder on the Strategy

Tree until you can see the I/O point you want to change. Double-click the I/O point name.

2. In the Edit Analog Point or Edit Digital Point dialog box, make the necessary changes. Click OK to save.

Deleting a Configured I/O PointYou cannot delete an I/O point that is referred to in the strategy.

CAUTION: Be careful when deleting I/O points. You cannot undo a deletion.

1. With the strategy open in Configure mode, expand the I/O Units folder on the Strategy Tree until you can see the I/O point you want to delete.

2. Right-click the I/O point’s name and choose Delete from the pop-up menu.

You can also delete an I/O point from the Configure I/O Points dialog box by highlighting its name and clicking Delete.

Configuring PID LoopsPID loops (or simply PIDs) are used to drive an input (a process variable) toward a particular value (the setpoint) and keep the input very close to that value by controlling an output. For example, consider temperature control, where the input is a measurement of ambient temperature, the setpoint is the desired temperature, and the output is a heater. The PID for this system will use a mathematical formula that controls the output to maintain a desired temperature, efficiently adjust to changes in setpoint, and compensate for changes in load, such as the influx of cold air. In this example, a temperature sensor (analog input), a thermostat (analog input), and a heater control (analog output) are components of one system, controlled by a PID loop.

This guide assumes that you are already familiar with using PIDs. PID calculations are complex and the physical qualities of systems suitable for PID control differ greatly. This guide includes only basic information for configuring PIDs.

SNAP PAC I/O units support 96 PID loops.

PIDs can control isolated systems or be part of cascaded systems where one loop controls the setpoints or input variables of others. For maximum flexibility, any PID input, setpoint, or output can be determined by PAC Control commands.

CONFIGURING PID LOOPS


PIDs and StrategiesThe PID operates at the I/O unit, independently of the controller. However, the controller supports logic commands to read and write various PID parameters and modes. Once configured and initialized, a PID operates until the I/O Unit loses power.

When you change PID configuration in PAC Control, remember that changes are not written to the I/O unit until the strategy is downloaded and run. For a SNAP PAC I/O unit, be sure to save PID configuration to flash memory following instructions for the I/O unit.

If you subsequently download a different strategy to the control engine, you’ll receive an error message (-700) reminding you that a PID loop is still running and that it may conflict with the new strategy. To turn off a PID loop, open PAC Manager and use Inspect mode to change the PID’s algorithm to None.

Each PID loop must be individually configured and tuned.

Configuration steps start in “Adding a PID Loop” on page 142, and tuning steps are described in “Inspecting and Tuning PID Loops” on page 153. For additional information, see “PID—Ethernet Commands” on page 302, and Opto 22 form 1641, OptoTutorial: SNAP PAC PID.

Adding a PID Loop1. With the strategy open and in Configure mode, double-click the I/O Units folder (not


The Configure I/O Units dialog box opens.

2. Select the I/O unit the PID will be on, and click PID Loops.



3. Double-click the lowest unused number.

The Add PID Loop Dialog appears.

4. Complete the fields as described in “Add PID Loop Dialog Box” below.5. Click OK.

The new PID appears in the Configure PID Loops dialog box.

6. When you have finished configuring PIDs, click Close.

PIDs appear in the Strategy Tree under the I/O unit.

PID loops



Add PID Loop Dialog Box

A—Name. Type a unique, descriptive name for the PID. The name must start with a letter and may contain letters, numbers, and underscores (spaces are converted to underscores).

B—Description. (Optional) Enter a description of the PID.

C—Input. Select the type of input: I/O Point, Host, or PID Output.

• If the PID’s process variable comes from an I/O point on the same unit, select I/O Point. Choose the point from the drop-down list or type a point name to configure a new point.

• If the PID’s process variable comes from the PAC Control strategy, select Host. Enter an initial value for the input.

• If the PID’s process variable is the output of another PID on this brain (a cascading control loop), select PID Output. Choose the PID from the drop-down list.

D—Square Root. (Optional) If you chose I/O Point or PID for step C, check this box if the error should be calculated based on the square root of the process variable (applies to flow

A

C

E

B

H

F

G

I

K

J

D

LM

N

O

P



control systems where volumetric flow is proportional to the square root of a signal from a flow transducer).

E—Low/High Range. Set the valid range of the process variable by entering the low range and the high range. (See Output Options for optional responses to out-of-range input.)

F—Setpoint. Choose the source for the setpoint: I/O Point, Host, or PID Output.

• To control the setpoint using a device (on the same brain) such as a potentiometer, select I/O Point; choose an I/O point from the drop-down list or type a new point name.

• To control setpoint using PAC Control or PAC Display, select Host. For Initial Value, enter the most common operating value.

• If another PID loop will control the setpoint, select PID Output and choose the PID from the drop-down list.

G—Output. Choose the destination for the PID output: I/O Point or Host. (To use the output for controlling the setpoint or input of another PID, choose Host.)

H—Lower Clamp/Upper Clamp. Enter upper and lower clamp values to prevent the output from exceeding a desirable range. These values should equal the range of the output point, if used. Or choose values to make sure that the output device doesn’t shut off (for example, keeping a circulation pump running regardless of the PID output) or that the output never reaches a destructively high setting (for example, keeping a motor below maximum).

I—Min Change/Max Change. (Optional) Enter minimum and maximum change values. The output won’t respond until the minimum change is reached (for example, you may not want a heater to turn on to correct a 1 degree error). Maximum change prevents too drastic a change in output (for example, you could limit the increase in a pump’s output to prevent pipe breakage). The default for both minimum and maximum is zero, which disables the feature.

J—Output Options. Choose how the PID should respond if the input goes out of range.To have PAC Control logic or an operator respond, check Switch to manual mode. To force the output to a specific value, check that option and type the output values.

NOTE: If both boxes are checked (forced output and manual mode), the output will be forced and the PID put into manual mode; but if the PID is already in manual mode, the output will not be forced. (You can use the command Get PID Status Flags to determine current settings.)

If neither box is checked and the PID input goes out of range (as defined by E– Low/High Range) then the output will freeze, but only while the input is out of range.

K—Algorithm. Choose algorithm: Velocity, ISA, Parallel, Interacting. For details on algorithms, see “Algorithm Choices (PID)” on page 303.



L—Mode. Choose the Mode you want the PID to be initialized to. The main difference between Automatic and Manual mode is that in Manual mode the PID loop stops its mathematical calculation. In both modes the PID's output value is still copied to the analog output.

• Auto mode: The PID makes calculations based on the difference between the input and the setpoint resulting in changes to the output, which causes the input to move toward the setpoint.

• Manual mode: The PID stops making changes to the output, but continues to write the PID output to the analog point (or configured destination for the PID output). Manual mode allows PAC Control logic or an operator to control the PID output, which in turn is written by the PID loop to the analog point (or configured destination of the PID output).

NOTE: If the value of the analog point or configured destination is changed, it will be overwritten by the PID output.

M—Scan Rate. Enter a scan rate to determine how often the input is scanned and the controller output is calculated. Minimum value is 0.001 (1 ms). Scan time should be greater than system lag (the time it takes for the controller output to have a measurable effect on the system). Also consider other PIDs and tasks on the brain competing for processing power.

N—Gain. Type a positive or negative value for Gain. Heating systems usually require a negative value and cooling systems a positive value. NOTE: Gain is usually refined during the tuning process.

O—Fd Fwd Initial/Fd Fwd Gain. (Optional) Enter Feed forward Initial and Feed forward gain values if you need to offset the controller output in your application. These values are constants that are multiplied and added to the controller output; often they are not used in PIDs.

P—Tune I/Tune D. (Optional) Type Integral and Derivative settings if you know the desirable settings. However, Integral and Derivative are not essential to basic configuration and are better determined in the tuning process.

AnalogOutputInput Output

SetpointPID



Changing a PID LoopYou can change the PID loop’s configuration and its position in the I/O unit.1. Make sure the strategy is open and in Configure mode. On the Strategy Tree, expand

the I/O Units folder until you see the PIDs folder for the I/O unit you want. Double-click the PIDs folder.

The Configure PID Loops dialog box opens, listing all configured PID loops. Remember that the number of PID loops available depends on the I/O unit.

PID loops are scanned by the I/O unit in the order that they appear in this list.

2. To move the PID loop to a different position on the I/O unit, use the up- and down-arrows in the dialog box.

3. To change the PID loop’s configuration, double-click its name to open the Edit PID Loop dialog box. Change the fields as necessary.

For help in completing the fields, see “Adding a PID Loop” on page 142.

Deleting a PID LoopOnly PID loops that have a reference count of zero can be deleted. Be careful when deleting PID loops; you cannot undo a deletion.1. Make sure the strategy is open and in Configure mode. On the Strategy Tree, expand

the I/O units folder until you see the PID loop you want to delete.2. Right-click the name of the PID loop and choose Delete from the pop-up menu.

The PID loop is deleted.

You can also delete a PID loop in the Configure PID Loops dialog box by highlighting it and clicking Delete.

Up- and down- arrows

INSPECTING I/O IN DEBUG MODE


Inspecting I/O in Debug ModeYou may want to inspect or change I/O while you are running your strategy in Debug mode. This section shows how to view information about I/O and make changes while the strategy is running.

To monitor several I/O elements at once in a window you can save with your strategy, see “Using Watch Windows for Monitoring” on page 165.

Inspecting I/O Units and Saving Settings to Flash1. With the strategy running in Debug mode, double-click an I/O unit in the Strategy Tree.

The Inspect I/O Unit dialog box appears, showing information about the unit and its points. The title bar shows the name of the I/O unit and whether scanning is occurring.

NOTE: Scanning stops whenever you click a changeable field. It resumes once you click Apply, another button, or an unchangeable field. If scanning resumes before you click Apply, any changes you made are lost.

2. To save the current configuration of the I/O unit to its EEPROM (flash memory), click the Information tab and then click the Set button under Stored Configuration (Flash EEPROM).



The following parameters are saved:

NOTE: Use this option to protect the I/O unit configuration information from being lost when the power is turned off. You should save the configuration settings to flash when they are final.

Saving to flash memory this way is the same as saving to flash by other methods, such as using PAC Manager (see the PAC Manager User’s Guide), and is preferable to using the command Write I/O Unit Configuration to EEPROM.

3. To reset saved parameters to their powerup default values, click the Clear button.4. To change the I/O unit’s current status, click an arrow in the Enable Comm field. Then

click Apply.

Yes on a green background means enabled; No on a red background means disabled. If you change it, the background turns magenta until you click Apply.

5. To view an individual I/O point, highlight its name in the list.

– To add an I/O element to a watch window, click Add Watch. See page 165.

– To open an inspection window to change an I/O point, click View. Then see “Inspecting Digital I/O Points” below for the I/O point you are changing (analog or digital).

6. When you have finished inspecting the I/O unit, click Close.

Inspecting Digital I/O Points You can inspect a digital point’s data, change its status, or set its internal values or external values in Debug mode. To monitor the point in a watch window, see page 165. To change the point, follow these steps.1. With the strategy running in Debug mode, double-click the I/O point on the Strategy

Tree. Or double-click an I/O unit in the Strategy Tree, click the Points (Compact) tab of the Inspect I/O Unit Dialog box, and then double-click the I/O point.

The small dialog box that appears shows the IVAL and XVAL.

– The XVAL, or external value, is the “real” or hardware value as seen by the I/O unit. This value is external to the control engine.

– The IVAL, or internal value, is a logical or software copy of the XVAL that is in the control engine. The IVAL may or may not be current, since it is updated to match the XVAL only when a strategy in the control engine reads or writes to an I/O point.

Analog Digital

• I/O module configuration• Initial output settings• Comm link watchdog time• Temperature conversion type• Input offset and gain settings

• I/O module configuration• Comm link watchdog time



If the digital point is configured with a counter, the counter values appear instead of the point’s status.

2. To change the value or to view more information, click the Maximize button.

The title bar shows the name of the digital point and whether scanning is occurring.

Scanning stops whenever you click a changeable field. It resumes once you click Apply, another button, or an unchangeable field. If scanning resumes before you click Apply, any changes you made are lost. Use the Clear button to immediately clear the field.

Asterisks in a field indicate an out-of-range value. Dashes in an XVAL field indicate a communication error.

3. Change the fields as necessary:

A—State The point’s current internal value. Switch between On and Off; then click Apply.

B—XVAL. The point’s current external value. Switch between On and Off; then click Apply.

C—On-Latch/Off Latch The state of the point’s on and off latches.

D—Counter Internal and external feature values if the point has been configured with any special features, such as a counter.

Maximize

A

D

B

C

E



E—Enable comm Current point status: Yes on a green background means enabled, No on a red background means disabled. To change the status, click one of the arrows; then click Apply.

4. To add the point to a watch window, click Watch and see page 165.5. To view configuration information for the variable, click More Info.6. To inspection I/O unit’s configuration, click Open Parent.7. (Pro only) To add a plot control, click Plot.

The Data button allows you to save, copy, or print the current plot. Use the Time Axis button to adjust the resolution. Click Include IVAL to see a concurrent plot of the IVAL.

Inspecting Analog I/O Points You can review an analog point’s data, modify its status, or set its internal values or external values in Debug mode. To monitor the point in a watch window, see page 165. To change the point, follow these steps.1. With the strategy running in Debug mode, double-click the I/O point on the Strategy

Tree. Or double-click an I/O unit in the Strategy Tree, click the Points (Compact) tab of the Inspect I/O Unit dialog box, and then double-click the I/O point.

The small dialog box that appears shows the IVAL and XVAL, as well as the units.

– The XVAL, or external value, is the “real” or hardware value as seen by the I/O unit. This value is external to the control engine.

– The IVAL, or internal value, is a logical or software copy of the XVAL that is in the control engine. The IVAL may or may not be current, since it is updated to match the XVAL only when a strategy in the control engine reads or writes to an I/O point.

Maximize



2. To change the value or to view more information, click the Maximize button.

The title bar shows the name of the analog point and whether scanning is occurring.

Scanning stops whenever you click a changeable field. It resumes once you click Apply, another button, or an unchangeable field. If scanning resumes before you click Apply, any changes you made are lost.

Asterisks in a field indicate an out-of-range value. Dashes in an XVAL field indicate a communication error.

3. Change the fields as necessary:

A—IVAL. The point’s current internal value. You can change it to any value within the valid range of the analog point. For an input, the valid range may exceed the apparent range; that is, you may be able to enter a value lower than the zero-scale value or higher than the full-scale value. For an output however, you cannot enter a value outside of the range defined by the zero-scale and full-scale values. After you change it, click Apply.

B—XVAL. The point’s current external value. You can change it to any value within the valid range of the analog point; then click Apply.

C—Enable comm. Current point status: Yes on a green background means enabled, No on a red background means disabled. To change the status, click one of the arrows; then click Apply.

4. To add the point to a watch window, click Watch and see page 165.5. To view configuration information for the variable, click More Info.6. To inspect the I/O unit’s configuration, click Open Parent.7. (Pro only) To add a plot control, click Plot.

A B

C



The Data button allows you to save, copy, or print the current plot. Use the Time Axis and Value Axis buttons to adjust the resolution. Click Include IVAL to see a concurrent plot of the IVAL.

Inspecting and Tuning PID LoopsIn Debug mode, you can view PID loops and tune them. This section gives you basic steps for inspecting PIDs, determining system lag, and tuning PIDs. See also, Opto 22 form 1641, OptoTutorial: SNAP PAC PID, which we highly recommend. Form 1641 is available for download from our website at www.opto22.com.

Inspecting a PID1. With the strategy running in Debug mode, double-click the PID on the Strategy Tree.

INSPECTING AND TUNING PID LOOPS


2. View or change PID parameters as necessary. Click the other tabs to see additional data. To tune the PID, see page 159.

3. To add the PID to a watch window, click Add Watch and see page 165. 4. To save, copy, or print the current plot, click the Data button and choose from the

pop-up menu.5. To save changes to any of the PID configuration parameters, click Save Tuning.

Determining System LagYou can directly control the PID output to determine system lag, which is essential to setting the PID scan rate. Also see Opto 22 form 1641, OptoTutorial: SNAP PAC PID, available for download from our website at www.opto22.com.1. Determine two significantly different output settings that are within the capabilities of

your system.2. With the strategy running in Debug mode, double-click the PID on the Strategy Tree.

Click a tab to see or change additional data.

Setpoint and Input plot. Adjust resolution using the Input Axis button below the plot. Click and drag on the scale to move the line.

Output plot. Adjust resolution using the Output Axis button. Click and drag on the scale to move the line.

Time axis. Adjust resolution using the Time Axis button. Click and drag left or right to see other times.



3. Set the Mode to Manual (if not set already) and click Apply.4. In the Output field, type one of your two output settings and click Apply.

Use an output value typical of your system but low enough to allow you to change output by 20%.

5. Reset your time axis, if necessary, by clicking the Time Axis and choosing from the pop-up menu. Then choose Reset Scale Tracking from the same menu.

The span setting varies according to your system; a 3-minute span is often suitable. Until you are familiar with the PID plot, it is recommended that you avoid using the shortest settings (10-seconds or 1-second). After you’ve observed a change in the input, you can zoom in on the graph, which is described later.

6. Wait for your system to stabilize.

The system is stable when the Input value does not vary significantly (some drift can be expected). Stabilization may take several minutes, depending on the system.



7. Increase the resolution of the Input Axis by clicking the Input Axis menu and choosing a span setting of 1 or 5 percent.

8. Center the Input Axis, if necessary, by clicking the red line at its left end and dragging it up or down until the plot is visible.

9. Under the Time Axis menu, choose Reset Scale Tracking.

This is a precautionary step, as changing settings on the plot can fix the plot at a certain point in time. Resetting the time axis ensures that you are viewing the real-time values.

10. In the Output field, type the other of your two output settings and click Apply.

A 20% percent increase is a moderate, detectable change for most systems. Your system may require a larger or a smaller change to stay within safety constraints.

11. Wait for a discernible change in the Input axis.

A stable system exhibits little change in the Input value, which is shown numerically and graphically.

Adjust resolution of the Input Axis by clicking the Input Axis button.



12. Increase the resolution of the Time Axis by clicking the Time Axis button and choosing a lower percentage, such as View 1 Minute Span.

13. Scroll the Time Axis to locate the point at which you changed the Output.

Both the time and input axes should display the point at which the Output changed, the lag, and the point the input changed. If not, adjust the Input axis and Time axis, until this information is displayed.

14. From the Data menu, select Cursor.

The data cursor, a line with a value bar attached to it, appears on the plot.

15. Right-click the data cursor and choose Delta X from the Style submenu, as shown below.

The Input axis (indicated by the upper white arrow added to this picture) begins to respond to the change in output (lower white arrow).



16. To measure the system lag (the time between the change in output and the change in input), click and drag the first vertical red bar to just after the output change. Drag the second bar to just before the change in input.

If you are unable to get the precision you want, you can view the plot at a lower time span, such as 10 seconds. You will need to reposition your plot and the measurement bars of the Delta X cursor.

The example above shows a system lag of 1.88 seconds. Generally, a suitable scan rate can be anywhere from one-third the system lag to two times the system lag. Considerations in setting scan rate are:

The Delta X cursor displays the time difference between the two vertical bars.

Drag the first bar into position after the Output change.

Drag the second bar to a position just before the change in Input.



• Slower scan intervals may be easier to tune. The PID controller has time to see the effect of the previous output before calculating a new output.

• Faster scan rates may be necessary to achieve the desired response. When scan intervals are shorter than the system lag, tuning must compensate for any over-correction from the controller output.

Tuning a PID LoopTuning a PID involves manipulating the P, I, and D constants in real time. The following steps should be viewed as general suggestions to show you features that are available for tuning. We highly recommend Opto 22 form 1641, OptoTutorial: SNAP PAC PID, for more detailed information. Form 1641 is available for download from our website at www.opto22.com.

CAUTION: Before following these procedures, make sure you know the limits of the equipment being controlled and monitored by your PID loop. Also, make sure that these points are configured properly. Any values suggested in these steps are for example only and must be modified according to the capabilities and constraints of your system.

1. Make sure the following PID features have already been configured:

– Scan Rate

– Input

– Input low range and high range

– Output

– Output lower and upper clamp.

– Algorithm

– Setpoint. If your setpoint changes during normal operation, tune your PID with the setpoint configured to host, so you can simulate setpoints from an input point or from another PID.

– Gain. A final gain constant will be determined by tuning, but before you can tune your PID, your gain constant must be either a positive or negative number according to the type of system you have. For example, a heating system reports a negative error when heat needs to be applied; a negative gain constant turns this error into a positive output for the heater. Alternatively, a cooling system reports a positive error when the input exceeds the setpoint; a positive gain constant maintains the positive output to the chiller.

– Optional, depending on your system: Minimum and maximum changes to Output and Output forcing when the Input is out of range.

2. Download and run your strategy.

The current PID configuration is written to the I/O unit. You can stop your strategy at this point if you wish, as the PID will continue operating.

3. In Debug mode, double-click the PID on the Strategy Tree.



4. Set the PID Mode to Auto (if not set already) and click Apply.5. Change the Setpoint, if desired, by typing a new setpoint and clicking Apply. (Setpoint

must be configured as Host.)

Depending on the type of system, your PID may maintain a setpoint or respond to changes in setpoint. Experiment with setpoint changes again after tuning the P, I, and D constants.

6. Adjust the span of the input, output, and time axes according to how much change you expect from your system. To set a span, click the axis button and choose from the pop-up menu.

7. If desired, type a new Scan Rate and click Apply.

For most systems, you should use an appropriate scan rate based on the system lag (see “Determining System Lag” on page 154). However, you can experiment with Scan Rates before tuning the P, I, and D constants or adjust scan rate after tuning.

Here is an example for Scan Rate:



8. Experiment with gain settings by typing a new value in the Gain field and clicking Apply.

The easiest way to tune most PIDs is to experiment with the gain constant first. Try various gains to see how well the system stays at setpoint and responds to setpoint changes.

In the example below, the white arrows (added for the example), show where gain constants of -2, -5, -10, and -20 were applied:

The lag for this system was determined to be about 2 seconds. The left half of the plot reflects a 0.5-second scan rate, while the right half shows a 3-second scan rate. Notice both scan rates have the same effect on the input; however, the 3-second scan rate is using less of the processor’s resources.



In this example, a gain setting of -30 revealed an offset error:

9. Experiment with the integral constant: in the Tune I field, type a number between 0 and 1 and click Apply. (Your PID may require larger numbers.)

With only a gain constant applied, the input often stabilizes at an incorrect value. In this heating example, a gain setting of -30 drove the input close to the setpoint, but subsequent increases failed to eliminate the offset. It is time to try integral constants to eliminate the offset error.



In this example, an integral constant of 0.1 corrected the offset error.

10. If derivative correction is needed, experiment with the derivative constant: in the Tune D field, type 1 and click Apply. (Your PID loop may require a larger number.)

In this example, a derivative of 10 makes a noticeable difference in keeping the input near the setpoint.

The far left side of the plot shows the offset before an integral constant of 0.1 was applied. This setting eliminated the offset. In many applications, a minor fluctuation around the setpoint is acceptable, and these applications use gain and integral only. In some applications, however, the fluctuations at the setpoint indicate that the gain is too high (too much gain makes a system unstable) or that a derivative constant is required.



11. Click Save Tuning to save your tuning parameters to the strategy database.

Changes are lost unless you save them. You may wish to save your tuning parameters when you see any improvement in performance, even if they are not final.

12. Click Yes.

Many PID systems are effectively controlled with gain and integral constants only and no derivative constant. In this example, the gain and integral settings are maintaining the temperature at 0.06 from setpoint. To demonstrate the effect of the derivative constant, the resolution of the input axis was increased to show a 1 percent span. At this resolution, the plot reveals changes of 0.01 degrees F.

The left side of the plot shows the effect of gain at -30, integral at 0.1, and no derivative constant. The arrow shows when a derivative constant of 10 was applied. The right side of the plot shows how the derivative constant is keeping the input closer to setpoint.



Values are saved to the PAC Control strategy. Remember to save PID parameters to the I/O unit’s flash memory, too (see “Inspecting I/O Units and Saving Settings to Flash” on page 148).

Using Watch Windows for MonitoringWhile the strategy is running, you can monitor several strategy elements at once in a watch window: I/O units, digital and analog points, PID loops, variables, even charts. You cannot monitor subroutine parameters or variables that are local to a subroutine in a watch window.

Unlike inspection windows, watch windows can be created the way you want, docked in a position most convenient for you, and are saved with your strategy. You cannot change strategy elements in a watch window, but you can open the inspect dialog box from the watch window and change the element there.

Creating a Watch Window1. With the strategy open and in Debug mode, choose Watch > New.2. In the Create New Watch Window dialog box, navigate to the location where you want

the watch window file to be kept (usually in the same folder as the strategy). Enter the watch window file name and click Open.

The empty watch window appears.

3. Add elements you want to watch in this window by clicking them on the Strategy Tree and dragging them into place in the watch window, or by right-clicking them and choosing Watch from the pop-up menu.

You can add I/O units, digital and analog points, PID loops, variables, and charts. You cannot add subroutine parameters or variables that are local to a subroutine.

Depending on which element you add and how you add it, it may appear immediately in the window, as shown here.

USING WATCH WINDOWS FOR MONITORING


For some elements, the Add Watch Entry dialog box appears, so you can specify what to watch.

4. If an Add Watch Entry dialog box appears, click to place or remove the check mark next to any item. When all the items you want to watch are checked, click OK.

The element is added to the watch window.

The watch window is automatically saved.

Opening an Existing Watch WindowIf a watch window was open when you exited Debug mode, it will automatically open again when you re-enter Debug mode. To open other watch windows, follow these steps.1. Make sure the strategy is open and in Debug mode.2. Choose Watch > Open.3. Navigate to the watch window you want to open and double-click its name.

The window opens in the position you left it.

Items in this area vary depending on the element you are watching. This example shows a chart.



Working in Watch WindowsWatch windows are flexible. You can dock the window where you want it in the PAC Control main window. You can also move, delete, and inspect elements in the window.

• To dock the watch window, click the docking button in its title bar.

The window moves to its own frame.

See “Docking Windows” on page 63 for more information.

• To expand or collapse watch window you have added to an I/O unit, PID loop, chart, or table, click its plus or minus sign.

“Docked” watch window

Expand or collapse the item by clicking the + or - sign in the box.

USING WATCH WINDOWS FOR MONITORING


• To rearrange elements in the watch window list, click the item you want to move and drag it to a new location, or right-click it and choose Move Up or Move Down from the pop-up menu.

You can also sort elements in the window by clicking on the column label. For example, to sort by Type, click the label Type in the column heading. Click again to change the order from ascending (A–Z) to descending (Z–A).

• To move an element from one watch window to another, open both windows and drag the element where you want it. To copy an element to another watch window (so it will appear in both windows), hold down the CTRL key while you drag it.

• To delete an element, right-click it and choose Delete from the pop-up menu.

• To inspect an element, double-click it.

The inspect dialog box opens. For information on using it, see “Inspecting Control Engines and the Queue” on page 109.


7: 7: Working with StrategiesChapter 7

7: Working with Strategies

IntroductionA strategy is the software program you create in PAC Control. A strategy is similar to a file in any Microsoft Windows program. You use standard Windows menu items to create a new strategy, to open an existing strategy, or to save a strategy. The strategy includes all the definitions and instructions necessary to control your process. This chapter is a step-by-step reference for working with strategies in all three strategy modes: Configure, Debug, and Online.

In this ChapterCreating a New Strategy........................................ 169Opening a Strategy.................................................. 170Saving and Closing .................................................. 171Saving a Strategy to Flash..................................... 173Compiling and Downloading ............................. 175Running a Strategy Manually .............................. 184Debugging .................................................................. 185Viewing and Printing .............................................. 192Searching and Replacing ...................................... 203Legacy Options.......................................................... 207

Creating a New StrategyEach PAC Control strategy must be located in its own directory. When you create a new strategy you must create a new directory or use an empty one. Having each strategy in its own directory keeps all its files in one place and makes it easy to copy a strategy to another location for modification or backup.1. To create a new strategy, select File > New Strategy, or press CTRL + N, or click the New

Strategy button on the toolbar. 2. In the New Strategy dialog box, navigate to the directory where you want the strategy

to be placed. Create a new folder if necessary.

OPENING A STRATEGY


3. Type the strategy name.

As you can see in the Files of type field, PAC Control files have an extension of .idb.

4. Click Open.

The new strategy is created. Its Strategy Tree and Powerup charts appear in the PAC Control main window. For information on the main window, see “PAC Control Main Window” on page 56. For programming information, see “4: Designing Your Strategy.” For steps to create charts, see “8: Working with Flowcharts”

Opening a StrategyOnly one strategy at a time can be open in PAC Control. If you currently have a strategy open, it must be closed before another is opened. You are prompted to save changes before it closes.

Opening an Existing Strategy1. To open an existing strategy, select File > Open Strategy, or press CTRL + O, or click the

Open Strategy button on the toolbar.2. In the Open Strategy dialog box, navigate to the strategy you want to open and click

Open.

The strategy opens in Configure mode, with the windows in the same position they were when the strategy was closed.

Opening an ioControl StrategyIf you have been using ioControl Basic or Professional with a SNAP PAC controller, migration to PAC Project Basic or Professional is simple. Because the individual programs within the suite are essentially the same (although they have new features and hardware support), you can simply open a strategy in PAC Control and then save it. For safety, we recommend you back up all ioProject files before opening them in PAC Project. See also, “Opening Strategies in PAC Control Basic and PAC Control Professional” below. For more information on migrating your system to SNAP PAC, see form 1680, the SNAP PAC System Migration Technical Note.

Opening a Recently Used StrategyTo open a strategy you have recently used, choose its name from the list at the bottom of the File menu. The ten most recently opened strategies are listed.

CHAPTER 7: WORKING WITH STRATEGIES


Loading a Strategy or Mode at StartupTo have PAC Control automatically start up with the strategy that was open when you exited, choose Configure > Options and click to put a check mark next to Load Last Strategy at Startup.

To have PAC Control open strategies in the same mode as when you exited PAC Control, choose Configure > Options and click to put a check mark next to Load Last Mode at Startup.

Opening Strategies in PAC Control Basic and PAC Control ProfessionalA strategy saved in ioControl version 6.1 or less can be opened in either PAC Control Basic or Professional. A PAC Control Basic strategy can also be opened in PAC Control Professional. However, PAC Control Professional strategies cannot be opened in Basic or in any earlier version of PAC Control.

CAUTION: Once a strategy is opened in PAC Control Professional, it can no longer be opened in PAC Control Basic.

Opening an OptoControl StrategyIf you are moving a strategy from OptoControl to PAC Control Professional, PAC Control will open it and help you convert it. Although many things will convert without difficulty, planning ahead is essential to make the job easier. Before opening an OptoControl strategy in PAC Control, read form 1692, the FactoryFloor to PAC Project Migration Technical Note.

Saving and ClosingCAUTION: Once a strategy is opened in PAC Control Professional, it can no longer be opened in PAC Control Basic.

Saving the Strategy and All ChartsTo save all your work quickly, choose File > Save All. The strategy and all modified charts and subroutines are saved.

Saving the Strategy and Some ChartsNOTE: You cannot save changes to a subroutine this way. To save a subroutine, use File > Save All, or use Subroutine > Save or Subroutine > Save All.

SAVING AND CLOSING


1. To save changes to some charts but not others, click the Save Strategy button on the toolbar (or choose File > Save Strategy, or press CTRL + S).

The Save Strategy dialog box appears, highlighting all charts modified since the last save. In this example, two charts have been modified:

2. To save some charts and not others, press CTRL and click any charts you don’t want to save.

You can also click Clear All to select none of the charts, or click Select All to select all of the charts.

3. When only the charts you want to save are highlighted, click OK.

The strategy and the highlighted charts are saved.

Saving the Strategy to a New Name1. To save the strategy and all its charts under a new name, choose File > Save Strategy

As. 2. In the Save Strategy As dialog box, navigate to where you want the new strategy to be.

Create a new folder if necessary.

Remember that each strategy must be in its own directory.

3. In the Strategy Name field, enter the new strategy name. Click Save.

The strategy and all its charts are saved under the new name in the new directory.

Saving Before DebuggingWhen you change to Debug mode, you are prompted to save a strategy you have modified. If you don’t want to be prompted to save before entering Debug mode, choose Configure > Options and click to remove the check box for Prompt To Save Strategy Before Running Debugger.



Closing a StrategyTo close a strategy, click the close box in the Strategy Tree or choose File > Close Strategy.

NOTE: Since only one strategy at a time can be open in PAC Control, creating a new strategy or opening an existing strategy automatically closes any current strategy first. If you’ve made changes to the current strategy, you are prompted to save them.

Saving a Strategy to FlashWhen you finish working on your strategy and have downloaded it, you should save it to the control engine’s flash memory. By default, a strategy is downloaded to the control engine’s RAM. Saving it to flash protects the strategy in case of a power loss. You can save it to flash just once, when needed, or save every time the strategy is downloaded.

Saving to Flash OnceYou can save the strategy to flash at any time when you are in Debug mode. To do so, choose Control Engine > Save Strategy to Flash.

Saving to Flash on Every DownloadCAUTION: It is possible to wear out flash memory if you save to it many, many times. Use the following steps only when your strategy is finished.

1. When you have finished the strategy and are in Configure mode, choose File > Strategy Options.

2. In the Strategy Options dialog box, click the Download tab. Check Save strategy to flash memory after download.

ARCHIVING STRATEGIES


If a control engine loses power and then restarts, the autorun flag tells the control engine to automatically start running the strategy that is in flash memory. If the autorun flag is not set, the strategy must be started manually after power is restored to the control engine.

3. To have the strategy run automatically after a control engine restarts, check Set autorun flag after download.

4. Click OK.

Archiving StrategiesStrategy archives help you track changes during development and provide a backup in case of a failure on the control engine or on the computer where the original files are kept. Archive files are date and time stamped, and zipped for compact storage. We recommend you archive both to the computer (during strategy development) and to the control engine (when the strategy is completed).

Archiving to the ComputerArchiving strategies to the computer is an excellent way to track changes over time and to produce a zipped file you can copy to another computer or disk for backup. Archives are always placed in the same folder as your strategy. Since a new archive file is created each time you archive a strategy, remember to manually delete any old archive files you do not want to keep.

PAC Control offers three ways to archive strategies to the computer:



• To make an archive at any time, choose File > Archive Strategy. A dialog box shows you the name and location of the archive file.

• To have an archive automatically created whenever the strategy is closed, choose File > Strategy Options. In the Strategy Options dialog box, click Archive strategy to disk when strategy is closed.

• To have an archive automatically created whenever the strategy is downloaded, choose File > Strategy Options. In the Strategy Options dialog box, click Archive strategy to disk when strategy is downloaded.

The archive file name will be in one of the following formats:

The date stamp (D) is in the format mm/dd/yyyy. In the examples above, the date is February 28, 2007. The time stamp (T) is in the format hh/mm/ss. In the examples above, the time is 51 seconds past 11:43 A.M.

Archiving to the Control EngineWhen you archive a strategy to the control engine, you are placing the zipped file in battery-backed RAM. If power to the control engine is lost, the archive is still there. Archiving to the control engine as well as the computer makes sure that an older strategy can always be found and updated, even after personnel changes occur and years pass.

Make sure there is sufficient memory in the control engine for the archive file. Battery-backed RAM holds 256KB total; in addition to the archived strategy, it stores persistent variables and variables that are initialized on strategy download.

For steps for archiving to the control engine, see “Archiving to the Control Engine” on page 115.

Compiling and DownloadingBefore your strategy can be tested or run, it must be compiled and then downloaded to a control engine. When a strategy is compiled, all the commands, OptoScript code, charts, and variable and I/O definitions it contains are verified and converted into a format that the control engine can understand. Then the strategy can be sent (downloaded) to a control engine. Only compiled strategies can be downloaded.

NOTE: Before you can download your strategy, make sure you have downloaded the latest firmware to your control engine. For instructions, see the controller’s user’s guide.

Archive method File name format

Manual archive or archive when strategy is closed Path\Filename.Archive.D02282007.T114351.zip

Archive on download Path\Filename.Download.D02282007.T114351.zip

Archive when downloading from online mode Path\Filename.Online.D02282007.T114351.zip

COMPILING AND DOWNLOADING


Compiling and Downloading in One Step NOTE: If you are using Ethernet link redundancy in PAC Control Professional, make sure you are downloading through the IP address you want to use, either the primary or secondary address. See “Using Ethernet Link Redundancy in PAC Control” on page 102 for more information.

1. With the strategy open in PAC Control, click the Debug mode button on the toolbar, or choose Mode > Debug.

Changing to Debug mode automatically saves and compiles the strategy, including all code in OptoScript blocks.

2. If you see a Powerup Clear Expected message, click OK.

A download warning message may appear.

This message tells you that the strategy to be downloaded doesn’t match the strategy already loaded on the control engine, either because it is a different strategy or because it has been changed since the last download.

3. To continue the download, click Yes.

As the strategy is compiled, the Compile Progress dialog box appears. This dialog may appear only briefly. However, if there are errors or warnings, the dialog box will stay open. You can copy the errors and warnings by clicking the right mouse button and selecting Copy All as Text.



If there are errors, the strategy will not compile. Click Close to continue in Configure mode.

If there are only warnings, click Close to continue in Debug mode.

If no errors or warnings occur, the Strategy Download dialog box appears.

The Strategy Download dialog box will vary somewhat depending on your settings.

NOTE: If you are using background downloading (see “Background Downloading” on page 179), while the strategy is downloaded, there may be a very slight degradation in performance. This is due to the overhead on the controller to process the strategy download.

4. (Optional) If there is already an active strategy which is set up to have an alternate strategy, and you want to switch strategies, click Switch & Run to stop the active strategy and run the strategy you just downloaded. Or, you can click Switch to stop the active strategy and make the new strategy the active one (but not yet running).

Cancel aborts the new download. The controller is left as it was before the download occurs.



When the download is complete, you are in Debug mode. (If you receive errors, see“A: Troubleshooting.”)

After switching strategies, you can switch back to the original strategy by choosing Control Engine > Inspect in Debug mode and use the Switch and Run or Switch button in the Inspect Control Engine dialog box, or you can use PAC Terminal. When the strategy is switched back, the persistent variables are created and compared.

Switching the StrategyIf there is already an active strategy which is set up to have an alternate strategy (as described in “Background Downloading” on page 179), and you want to switch strategies, do the following:1. In Debug mode, choose Control Engine > Inspect to open the Inspect Control Engine

dialog box.2. Choose either the Switch and Run or the Switch button.

The Switch & Run button stops the active strategy and runs the strategy you just downloaded. The Switch button stops the active strategy and makes the new strategy the active one (but not yet running).

When the strategy is switched (as described in the previous steps), the following operations occur:

• Persistent variables are compared. If the type and size of the persistent variable are consistent, the contents are copied. If the type and size do not match, a new persistent variable is created. New persistent variables are initialized to zero and new persistent strings are initialized to NULL (empty) strings.

• I/O unit configurations are compared. If the I/O unit configurations match, I/O will not be initialized.

• The Powerup chart is called.

See also, “Background Downloading” on page 179.

Compiling without Downloading Sometimes you may want to compile without downloading, just to see if a chart, subroutine, or strategy compiles correctly. You can compile the active chart or subroutine only, just the changes you have made to the strategy, or the entire strategy.

Compiling the Active Chart or Subroutine

Whenever a chart or subroutine window is open and active, you can compile just that chart or subroutine. To do so, in Configure mode, click the Compile Active View button on the toolbar, or choose Compile > Compile the Active Chart. The menu option shows the name of the chart or subroutine you are compiling.



As soon as you choose the menu option, the chart or subroutine is saved and compiled. You are alerted only if errors are found.

Compiling Changes Only

To compile just the changes since the strategy was last compiled, choose Compile > Compile Changes. The menu option shows the name of the strategy you are compiling.

As soon as you choose the menu option, the strategy and all modified charts and subroutines are saved and compiled. You are alerted only if errors are found.

Compiling the Entire Strategy

To compile the entire strategy including all charts and subroutines, in Configure mode, click the Compile All button on the toolbar, or choose Compile > Compile All. The menu option shows the name of the strategy you are compiling.

As soon as you choose the menu option, the entire strategy is saved and compiled. The Compile Progress dialog box appears. You are alerted if errors are found.

Downloading Only If your strategy has been compiled, you can download it again quickly. Downloading again is useful if you want to run your strategy from a clean slate by reinitializing any variables that are set only on a strategy download.

To download a strategy that has already been compiled, you must be in Debug mode. Choose Control Engine > Download Strategy.

The Download to dialog box appears and your strategy is downloaded.

Background DownloadingThe Background Downloading feature allows you to download an alternate strategy to a controller while the active strategy currently on the controller continues to run. With two different strategies downloaded to the controller you can switch rapidly from one strategy to the other.

This allows you to:

• Download a new or updated strategy to the controller and then optionally run it with minimal downtime. For larger strategies, downtime is dramatically reduced.

• Download and test a new or updated strategy but still keep the original strategy available. You can bring back the original very quickly, either by manually switching from one strategy to the other, or—if the original is still burned to flash—by cycling power.



You can use background downloading as an alternative to Online mode, which also allows you to make changes while a strategy is running. The following table describes the differences between Online Mode and Background Downloading:

To enable Background Downloading:

NOTE: Controller memory is cut in half when background downloading is set it in PAC Manager. Also, one chart is used for the alternate download port, so there is one less chart that can run.

1. Open PAC Manager and do the following steps:a. Click the Inspect button to open the Inspect window.b. In the IP Address field on the Inspect window, type the IP address for the SNAP PAC

controller.c. Click Status Write, then scroll down to Strategy Download Method.d. Click on the Value field for Strategy Download Method, select Background from the

drop-down menu, then click Apply.e. Under Operation Commands, highlight “Store configuration to flash,” and click

Send Command.The configuration is stored to flash memory and a Success message appears.

For more information, see the PAC Manager User’s Guide, form 1704.

2. Turn off the power to the control engine, and then turn it back on again.3. In Configure mode in PAC Control, choose File > Strategy Options.4. On the Download tab under Flash Memory, select “Use background downloading and

fast strategy updating.”5. (Optional) Under Flash Memory, select “Save strategy to flash memory after download.”

Online Mode Background Downloading

Can you add variables, I/O, and charts? No Yes

Can you add and change blocks, change instructions, and edit existing charts?

Yes Yes

What is downloaded in Debug mode?

Only the edited charts are downloaded. All other charts keep running.

The entire alternate strategy is down-loaded while the entire active strategy continues to run.

Where does the strategy restart after download?

The affected charts restart at block 0.

If you switch to the alternate strategy after download, the strategy restarts with the Powerup chart.

How is the controller mem-ory affected?

When a chart is downloaded, the old one is not deleted, so this consumes additional mem-ory. To clear memory, the strat-egy should be stopped and then compiled and downloaded.

Controller memory is cut in half when background download is set it in PAC Manager. Also, one chart is used for the alternate download port, so there is one less chart that can run.



6. (Optional) To have the strategy run automatically after a control engine restarts, select “Set autorun flag after download.”

7. Click OK.

PAC Control is now set to download the strategy in the background when you click the Debug mode button . Next, see “Compiling and Downloading” on page 175. See also, “Switching the Strategy” on page 178.

Downloading Without Using PAC ControlIf you are creating strategies for users who do not have PAC Control on their systems (for example, if you are an integrator or OEM), you can make a control engine download file that can be downloaded to a SNAP PAC controllerusing either the graphical interface in PAC Terminal or the command line interface with a batch file. This one download file is built for a specific control engine but can also be downloaded to other similar control engines. It contains everything PAC Control would download, including .per, .inc, and .crn files, control engine-specific files, and initialization information.

In most cases you will want the downloaded strategy to be saved to flash memory and to start automatically (autorun) when power is cycled to the control engine. Before you create the download file, follow the steps in “Saving to Flash on Every Download” on page 173. Check the boxes to have the strategy saved to flash memory after download and to set the autorun flag after download. This information will become part of the download file.

Creating the Control Engine Download (.cdf) File

With the strategy open in PAC Control in Configure mode, right-click the name of the control engine in the Strategy Tree and choose Compile Control Engine Download File from the pop-up menu. (You can also choose Compile > Compile Control Engine Download File.)



The file is created in the same folder as the strategy, with a .cdf extension and a filename consisting of the strategy’s name and the control engine’s name (for example, MyStrategy.MyEngine.cdf ).

Once the control engine download file is created, it can be downloaded using either the graphical interface in PAC Terminal or the command line interface with a batch file you create.

Downloading the .cdf File using PAC Terminal

1. Click the Windows Start menu and choose Programs > Opto22 > PAC Project 9.0 > Tools > PAC Terminal.

2. Right-click the name of the control engine you want to download the file to.3. In the pop-up menu, choose Download. In the submenu, choose Control Engine

Download File.



4. Enter the path and filename of the .cdf file, or click the Browse button and navigate to it. When the filename appears in the File to Download field, click OK.

The file is downloaded to the control engine.

Using Command Lines or a DOS Batch File to Perform PAC Terminal Tasks

If you do not want your end user to have to use PAC Terminal, you can use DOS-level commands or create a DOS batch file to download a .cdf file. In addition to downloading a .cdf file, the DOS commands can also run or stop a strategy, or define the control engine on the PC that will download the file. PAC Terminal must be installed on the PC where the batch file is used.

The following table lists actions you may want to take within PAC Terminal:

This example shows lines included in a batch file that will define the control engine, download the .cdf file to it, and then run the strategy:termcl -a MyCE tcp 10.20.30.40 22001 0 2000termcl -d MyCE "c:\My_Project\MyStrategy.MyCE.CDF"termcl -r MyCE

Changing Download CompressionIf you have a very large strategy, short timeouts, and slow connections on your network, you may need to decrease the compression level to download the strategy successfully. When you decrease compression, the strategy takes longer to download because it is sent in smaller chunks. If you are having difficulty downloading your strategy, follow these steps to decrease compression:1. With the strategy open in Configure mode, choose File > Strategy Options.2. In the Strategy Options dialog box, click the Download tab.

To do this Use this

Show help information for termcl -h control_engine_name

Download the specified file to the specified controller. Compression can be between 0 (none) and 10 (max). -d control_engine_name filename [-z compression]

Run the strategy in the specified control engine -r control_engine_name

Stop the strategy in the specified control engine -s control_engine_name

Send a Forth command to the control engine -c control_engine_name Forth_command

Add a control engine definition to the system. Does not modify an existing definition.Example: -a MyCE tcp 10.20.30.40 22001 0 2000

-a control_engine_name tcp ip-addr port retries timeout_ms

Download the encrypted SSD file to the controller -dp control_engine_name ssd_filename

Prevent response messages from printing to the DOS screen Append the DOS switch -q

RUNNING A STRATEGY MANUALLY


3. Move the slider to the left to reduce compression, and then click OK.

You may need to experiment with the setting until the strategy downloads successfully.

Running a Strategy Manually1. With the strategy open, choose Mode > Debug. 2. Click the Run Strategy button (or press F5, or select Debug > Run).

You can also run a strategy from the Inspecting dialog box. See “Inspecting Control Engines in Debug Mode” on page 109.

Running a Strategy Automatically (Autorun)You can set the strategy to run automatically (autorun) if the control engine loses power and then restarts. In traditional Opto 22 controllers, the OptoControl autorun function was controlled by a jumper. For PAC Control, it’s controlled by the autorun flag. If the autorun flag is not set, the strategy must be started manually after power is restored to the control engine. The strategy must be saved in flash memory for autorun to work.

You can set the autorun flag in two ways:

• In Configure mode, save the strategy to flash memory and set the autorun flag every time the strategy is downloaded. (Be careful you do not save to flash too often, as flash memory eventually wears out.) See “Saving to Flash on Every Download” on page 173.

• In Debug mode, save the strategy to flash memory by choosing Control Engine > Save Strategy to Flash. Then right-click the control engine in the Strategy Tree and choose

Slider



Inspect from the pop-up menu. In the Inspect dialog box, enable Autorun. (See “Inspecting Control Engines and the Queue” on page 109 for more on the Inspect dialog box.)

Protecting a Running StrategyIf you want a strategy to run automatically without interruption, you can protect the strategy by disabling all host communications to the control engine.

To protect the strategy, first make sure the strategy is saved to flash and that the autorun flag is set. To disable host communication, open PAC Manager and set the Control Engine port to 0, and then save that change to flash. For more information on setting this port, see form 1704, the PAC Manager User's Guide.

NOTE: This action also disables communication between PAC Display and the control engine.

Stopping a StrategyTo stop the strategy, click the Stop Strategy button (or press F3, or select Debug > Stop). You can also stop a strategy from the Inspecting dialog box; see “Inspecting Control Engines in Debug Mode” on page 109.

DebuggingOnce the strategy is running, if it doesn’t appear to be working correctly, you can use several tools in Debug mode to figure out what the problem is. You can pause a chart or subroutine; step into, over, or out of each block; watch it slowly step through the blocks; or add a breakpoint to a block to stop the strategy just before it executes that block.

The chart’s or subroutine’s status is shown in the lower left-hand corner of its window. This corner shows whether the chart or subroutine is running, stopped, or suspended, and whether the debugging tools, such as stepping and breakpoints, are in effect. The chart or subroutine must be running in order to use these tools.

Choosing Debug LevelYou can choose one of two levels of debugging:

• Minimal Debug lets you step from block to block, but does not allow you to step into blocks. Less information is downloaded to the control engine for minimal debugging, so downloading the strategy takes less time and less control engine memory. The strategy also runs slightly faster.

• Full Debug lets you step into blocks, so you can step through each instruction in an Action or condition block and through each line of OptoScript code in an OptoScript

DEBUGGING


block. If you are using OptoScript, you will probably want to spend the additional time to download your strategy at the full debug level.

To change debug level, make sure you are in Configure mode. From the Configure menu, choose Minimal Debug or Full Debug. The next time you enter Debug mode, the strategy will be compiled and downloaded with the new level.

Changing Debugger SpeedBefore you enter Debug mode, you may want to consider changing debugger speed. Depending on the number of charts and windows open in PAC Control, and depending on other processing your computer is doing at the same time, you may find that running the debugger affects the computer’s or the control engine’s performance of other tasks. If necessary, you can slow down the debugger by increasing the time delay between debugging calls to the control engine, therefore leaving more processing time for other tasks.

In addition, a slower setting may be useful when checking communication using PAC MessageViewer (see page 373).

To change debugger speed, follow these steps:1. With the strategy in Configure mode, choose Configure > Options. Alternatively, in

Debug mode, choose Debug > Options.2. In the PAC Control Options dialog box, click the Debugger tab.

3. Click and drag the slider to the speed you want.

The default speed is shown in the figure above. Since performance varies depending on your hardware and software, you may need to experiment to find the most efficient speed.



Pausing a Chart or SubroutineYou can temporarily stop any running chart or subroutine by pausing it. When you pause a chart or subroutine, it finishes the instruction it was executing, then stops at the next block (in Minimal Debug) or the next line (in Full Debug).

To pause the chart or subroutine in the active window, click the Pause Chart or Pause Subroutine button , or press F7, or select Debug > Pause Chart or Debug > Pause Subroutine. Here’s an example of a paused chart:

Hatch marks and a red outline appear on the Start block, indicating that this block is to be executed next. The status bar shows Step On, which means you can step through the chart or subroutine if you wish.

Stepping Through a Chart or SubroutineWhen you step through a chart or subroutine, you control the timing and execution of its commands in a running strategy. You can see what commands are being executed when, and you can monitor the status of variables and I/O that are affected by the commands.

There are two types of stepping: single-stepping and automatic stepping. Use single stepping to go through flowchart blocks at your own pace. Use auto stepping to watch the flowchart step automatically.

CAUTION: Since stepping through a running chart or subroutine—even auto stepping—slows down execution, be cautious if your strategy is running on real equipment. For example, stepping through a strategy might leave a valve open much longer than it should be.

Single Stepping

When you are debugging a strategy, start by using the Step Over button to go through a chart one block at a time. The Step Over button may be all you need to find any problems. If

Status bar—Step On

DEBUGGING


necessary, go back to Configure mode and change to full debug (see “Choosing Debug Level” on page 185) so you can step into blocks and execute one line at a time.1. Pause the chart or subroutine to be stepped through by pressing the Pause Chart or

Pause Subroutine button .

2. To step to the next command block, click the Step Over button (or press F10, or select Debug > Step Over).

The commands in the highlighted block are executed, the hatch marks move to the next command block, and the chart pauses again. Compare the chart below to the one on page 187. The hatch mark has moved to the next block.

3. If you need to step inside flowchart blocks and move through them one command at a time (or in OptoScript blocks, one line of code at a time), make sure you have downloaded your strategy at the full debug level. See “Choosing Debug Level” on page 185 for help.

4. If the chart or subroutine is not already paused, press the Pause Chart or Pause Subroutine button .

5. To step inside the block you are on (the one with the hatch marks), click the Step Into button (or press F11, or select Debug > Step Into).



6. To move from line to line, click either the Step Into or the Step Over button.

If a command within the block calls a subroutine, Step Into takes you into the subroutine. Step Over skips over the subroutine.

7. To step from a command inside a block and go to the next block, click Step Out .

Clicking Step Out when you are on a block, rather than inside it, unpauses the chart. In a subroutine, clicking Step Out takes you out of the subroutine.

Auto Stepping

Auto stepping lets you watch a chart’s or a subroutine’s logic in slow motion, one block at a time. A chart or subroutine does not have to be paused before auto stepping can begin. To begin auto stepping, click the Auto Step button , press F8, or select Debug > Auto Step Chart.

Step Auto appears in the status bar. The hatch marks move from block to block as each block’s commands are executed. When you reach a block whose code is currently being executed, the highlight around the block becomes changing shades of green instead of solid red (unless the block is executed very quickly).

A chart that contains flow-through logic stops when it has been stepped through. In a chart that contains loop logic, the auto stepping continues until you stop it by pressing the Auto Step button again.

The red arrow indicates the command that will be executed next.

The small gray tabs at the left of the white tab show how you got to where you are.

The white tab shows you where you are: inside a chart, a block, or a subroutine called by a chart.

The Step Into button takes you inside the current block, so you can step one command at a time.

DEBUGGING


Setting and Removing BreakpointsSometimes you want to see the action at one or two blocks without having to step through an entire chart or subroutine. You can use a breakpoint to stop a running chart or subroutine just before a block is executed.

You can set a breakpoint at any block in any chart or subroutine, whether it is running or stopped, paused or auto stepped. The strategy does not need to be running. You can set up to 16 breakpoints in one chart or subroutine. However, you cannot set a breakpoint inside a block.

To set a breakpoint, follow these steps:

1. With the chart or subroutine open and in Debug mode, click the Breakpoint tool .

The pointer turns into a hand.

2. Click the target block to mark it with the breakpoint hand.

A red square appears around the block and Break On appears in the status bar.

Breakpoint hand



3. Click other blocks to set additional breakpoints, or click blocks currently marked with a hand to remove the breakpoint.

4. When you have finished marking or removing breakpoints, click the Breakpoint button again or click the right mouse button within the window.

When the chart or subroutine runs, it pauses just before executing the breakpoint block. You can inspect variables or I/O points, disable strategy elements, change values, and so on to see the effect the block has.

5. To single step past the breakpoint, click the Step Block or Step Line button. Or to run the chart or subroutine at full speed after the breakpoint, click the Pause Chart button.

Managing Multiple Breakpoints You can see all the breakpoints you have set, and you can remove breakpoints one at a time or all at once. See also, “Setting and Removing Breakpoints” on page 190 to use the breakpoint tool.1. Press CTRL + B or select Debug > Breakpoints.

The Breakpoints dialog box appears, showing all the breakpoints set in the strategy.

2. To delete a breakpoint, highlight it and click Remove. To delete all breakpoints in the strategy at once, click Remove All.

Break On in status bar

Red square

VIEWING AND PRINTING


3. When you have finished making changes, click OK.

Interpreting Elapsed TimesAs you debug your strategy, you may notice elapsed time readings appearing in a chart’s or subroutine’s status bar, as shown below.

Elapsed time readings can help you determine how much time a chart, a subroutine, or a single block takes to execute. The readings have slightly different meanings depending on what you did to make them appear, as described in the table below:

Viewing and PrintingYou can view and print several helpful things in a strategy as described in the following topics:

When you . . . Elapsed time represents . . .

Run a chart or subroutine and pause it Time since the chart or subroutine started or was last paused

Single step (by line or block) Time to execute the previous block

Auto step Time to execute the most recently executed block

Hit a breakpoint Time since the last pause, or if the chart or subroutine was notpaused, elapsed time since it started running

Elapsed time



• “Viewing Strategy Filename and Path” (below)

• “Viewing an Individual Chart or Subroutine” on page 193

• “Viewing All Charts in a Strategy” on page 193

• “Printing Chart or Subroutine Graphics” on page 194

• “Viewing and Printing Strategy or Subroutine Commands” on page 197

• “Viewing and Printing Strategy or Subroutine Elements” on page 198

• “Viewing and Printing a Cross Reference” on page 200

• “Viewing and Printing a Bill of Materials” on page 201

For information on viewing and changing I/O units, see “Inspecting I/O in Debug Mode” on page 148. For variables, see “Viewing Variables in Debug Mode” on page 242.

Viewing Strategy Filename and PathTo see an open strategy’s filename and path, choose File > Strategy Information. A dialog box appears showing the path and filename.

Viewing an Individual Chart or SubroutineTo view an individual chart or subroutine, double-click its name on the Strategy Tree, or choose Chart > Open or Subroutine > Open. You can open as many of these windows as you need. The names of open windows appear on tabs at the bottom of the PAC Control main window. Click a tab to bring its window into view.

Viewing All Charts in a StrategyYou can see the status of all charts at once and change a chart’s status without having to open it. 1. Make sure the strategy is open and in Debug mode. On the Strategy Tree, double-click

the Charts folder.

The View Chart Status dialog box appears, showing every chart in the strategy:



2. To change the status of a chart, double-click the chart name.

The View Chart dialog box appears, showing the chart name, chart status, run mode, and breakpoint status. If the chart is paused (mode is Step On), the block at which it is paused is shown in the Paused At field. In the figure below, the chart is not paused:

The title bar shows whether scanning is occurring. Scanning stops when you click one of the changeable fields (Status, Mode, and Breakpoints) and resumes once you click Apply, another button, or one of the other fields. If scanning resumes before you click Apply, any changes you made are lost.

3. To stop, run, or suspend a chart, click an arrow in the Status field to select the option. Click Apply.

4. To turn pausing on or off, click an arrow in the Mode field to select Step On or Step Off. Click Apply.

5. To observe or ignore any breakpoints set in the chart, click an arrow in the Breakpoints field to select Break On or Break Off. Click Apply.

This action does not clear or set breakpoints, but just determines whether the chart stops at breakpoints when it is running.

Chart changes occur as soon as you click Apply.

6. To add the chart to a watch window so you can monitor it with other strategy elements, click Add Watch. In the dialog box, choose what to watch. Select an existing watch window to add this chart to, or create a new watch window.

See “Using Watch Windows for Monitoring” on page 165 for more information on watch windows.

7. When you have finished making changes, click Close to return to the View Chart Status dialog box.

Printing Chart or Subroutine GraphicsYou can print a chart or subroutine just as it appears on screen. You can also print all charts within a strategy. When printing a single chart or subroutine, you can preview the image to make sure it’s what you want before you print it.

NOTE: If you have trouble printing graphics, set your printer for PostScript emulation.



Setting Up the Page

Before printing graphics, you should verify your page setup, which determines how each graphic appears on a page. 1. In Configure mode, select File > Page Setup.

The Page Setup dialog box appears.

2. In the Graphics Scaling area, choose whether you want each flowchart to print at a fixed percentage of normal size or to span a specific number of pages.

– To print at a fixed percentage, click the Adjust To option and specify any scaling from one percent to 1,000 percent. You can type in a number or click the arrows to go up or down to the next increment of 25 percent. Typically, percentages between 50 percent and 200 percent work the best.

– To print to a specific number of pages, click the Fit To option and select the number of pages wide and tall you would like each chart to print. If you choose one for each dimension, each chart prints to a single page. For each dimension, you can specify any integer between one and 255, but be careful. Selecting values of five and five, for example, would cause each chart to print five pages wide and five pages long, a total of 25 pages.

3. (Recommended) To print a header on each page, put a check mark in the Print Header box.

The header lists the strategy name, chart or subroutine name, date and time of printing, page number, and column and row of the page with respect to the full chart printout.

4. Click OK to save your settings.

Previewing a Flowchart Printout

1. To see how a chart or subroutine will print before actually printing it, open the chart or subroutine window.

2. From the Chart or Subroutine menu, select Print Preview Graphics.



The preview window appears, showing the image as it will print. The cursor becomes a magnifying glass.

3. To zoom in at 200 percent, click where you want to see more closely. Click again to zoom in at 400 percent. Click a third time to return to 100 percent view.

You can also use the Zoom In and Zoom Out buttons at the top of the window to zoom in or out with respect to the top left corner of the image.

4. If the image spans more than one page, click the Next Page or Prev Page buttons to view the next or previous page. To switch between a single-page view and a double-page view, click the Two Page/One Page button.

5. To print, click the Print button to open the standard Windows Print dialog box. To change settings before printing, click Close and see “Setting Up the Page” on page 195.

Printing One Chart or Subroutine

1. To print one chart or subroutine, open its window. 2. From the Chart or Subroutine menu, select Print Graphics.3. In the standard Windows Print dialog box, do one of the following:

– To print to a printer, select the printer, page range, and number of copies. Click OK.

Magnifying glass cursor



– To print to a file, select Print to file and click OK. In the dialog box, enter the file name and location.

Your chart or subroutine is printed.

Printing All Charts in a Strategy

CAUTION: You can print all charts included in a strategy, but be sure that’s what you want to do before you begin. You cannot cancel once printing has started.

1. To print all charts within a strategy, open the strategy and check the page setup.

For help, see “Setting Up the Page” on page 195.

2. Select File > Print All Graphics.

Printing begins immediately; no Print dialog box appears. Messages inform you of each chart’s printing progress. To skip printing a particular chart, click Cancel when its message appears.

Viewing and Printing Strategy or Subroutine CommandsYou must be in Configure mode to view and print commands.1. To view all commands (instructions) in a chart or subroutine, open its window and

select View/Print Instructions from the Chart or Subroutine menu. Choose whether to sort instructions by block name or block ID number.

2. To view all instructions in an entire strategy, select File > View/Print > All Chart Instructions.

NOTE: Subroutine instructions are not included; you can print them separately.

PAC Control processes the information and displays it in the Instructions window.



You may need to resize the window and use the scroll bar to see all the data. Blocks and their instructions are listed in alphabetical or ID number order by type of block: action blocks first, then OptoScript blocks, then condition blocks, and finally continue blocks.

3. To print the data, click the Print button on the toolbar. To save it to a text file, click the Save button. To search the data, click theSearch button. When finished, close the window.

Viewing and Printing Strategy or Subroutine ElementsYou must be in Configure mode.1. To view a summary of I/O elements and variables configured in a strategy, select File >

View/Print > Database. 2. To view the same summary for a subroutine, open the subroutine window and select

Subroutine > View/Print > Database.

The View/Print Database dialog box appears.

Save SearchPrint



3. Make sure all element types you want to include are checked. Click to uncheck any elements you do not want.

4. To include descriptive comments associated with the elements, click to put a check mark next to Descriptions.

5. Click OK.

PAC Control processes the database and puts the data in the Database window.

You may need to resize the window and use the scroll bar to see all the data. For each element the name and reference count (that is, how many times the element is used in strategy commands) are shown, plus other information depending on the element type. The figure above shows numeric variables and communication handles.

Save SearchPrint



6. To print the data, click the Print button on the toolbar. To save it to a text file, click the Save button. To search the data, click the Search button. When finished, close the window.

Viewing and Printing a Cross ReferenceYou can view and print a report of every operand in your strategy or subroutine—charts, I/O units, analog points, digital points, communication handles, numeric variables, string variables, pointer variables, numeric tables, string tables, and pointer tables. The operands are cross-referenced to the charts, blocks, and instructions in which they are used.1. To produce a cross reference for a strategy, open it and select File > View/Print > Cross

Reference.2. To view a similar report for a subroutine, open the subroutine window and select

Subroutine > View/Print > Cross Reference.

PAC Control processes the data and puts it in the Cross Reference window.

You may need to resize the window and use the scroll bar to see all the data. Notice that the Instruction column (at right) shows the line number the operand appears in when it is in OptoScript code.


Save SearchPrint



Viewing and Printing a Bill of MaterialsYou can view and print a bill of materials (BOM) that lists all the I/O units and I/O modules (analog and standard digital) required to run the strategy. (Special-purpose modules, such as serial and high-density digital modules, are not included in the BOM.)1. To produce a BOM for a strategy, open it and select File > View/Print > Bill of Materials.

PAC Control processes the data and puts it in the Bill of Materials window.

You may need to resize the window and use the scroll bar to see all the data.


Viewing and Printing I/O Point MappingsYou can view and print a report that shows the location and mappings of I/O points. You can use this report as a look-up table for programming purposes. This can be useful with some commands that use different point mappings such as Move I/O Unit to Numeric Table Ex, Move Numeric Table to I/O Unit Ex, and IVAL Move Numeric Table to I/O Unit Ex.

This report basically provides the same information provided in the appendix Table Index Offset Examples in the PAC Control Command Reference, form 1701, but for the actual points in the strategy.1. To produce an I/O point mappings report for a strategy, open the strategy and select

File > View/Print > I/O Point Mappings.

Save SearchPrint



2. On the View/Print I/O Point Mappings dialog box, select the report style, either Formatted or Comma-separated, and select the position and mappings types, then click OK.

A report window appears.

What the columns mean:

Column Description

MOD The module number on the rack

CH The channel number within the module

4 4-channel mapping

8 8-channel mapping



Searching and Replacing You can search a chart, subroutine, or strategy for missing connections, empty condition blocks, or any command or operand. An operand is anything that can be affected by a command, including charts, I/O units, analog points, digital points, and all kinds of variables. Searching includes OptoScript code within OptoScript blocks.

You can also replace instructions or operands with similar items.

Searching You can search a strategy or one of its charts, or you can search a subroutine. 1. Open the strategy or subroutine and select Edit > Find.

The Find dialog box appears.

Or, if the item you want to find is listed in the strategy tree, such as a variable, table, or point, right-click the item and select either Find in the pop-up menu.

The item appears in the Find or dialog box automatically.

Point name

SEARCHING AND REPLACING


2. Under Search Scope, to search the entire strategy, click Global. To search one chart only, click Local and choose the chart name from the drop-down list.

If you are searching a subroutine, the search is Local and the subroutine’s name is shown.

3. Under Search For, choose one of the following:

– To search for a chart, an I/O unit or point, or a variable, click Operand. In the Type and Name fields, choose the operand you want from the drop-down list.

– To search for an instruction, click Instruction. Click Action or Condition, and choose the instruction you want from the drop-down list.

– To search for blocks that are not connected to other blocks, click Missing Connections.

– To search for condition blocks that have no instructions, click Empty Cond. Blocks.4. Click Find.

The dialog box expands and the search results appear at the bottom.

For more information on any item in the search results, try double-clicking the item.

Point name

Search results



5. To save the search results to a file or to print them, click Print. In the window that opens, click the Disk button to save or the Print button to print your search results.

6. When you have finished your search, close the Find dialog box.

Replacing You can also replace any operand, instruction, or tag with a similar item. As in searching, you can replace items in a strategy or one of its charts, or you can replace items in a subroutine. 1. Open the strategy or subroutine, and select Edit > Replace.

The Find and Replace dialog box appears.

Or, if the item you want to find is listed in the strategy tree, such as a variable, table, or point, right-click the item and select Replace in the pop-up menu.

The item appears in the Find and Replace dialog box automatically.

Point name

SEARCHING AND REPLACING


2. Under Search Scope, to search the entire strategy, click Global. To search one chart only, click Local and choose the chart name from the drop-down list.

If you are searching a subroutine, the search is Local and the subroutine’s name is shown.

3. Under Search For, choose one of the following:

– To search for a chart, an I/O unit or point, or a variable, click Operand. In the Find Type and Name fields, choose the operand you want to replace from the drop-down list. In the Replace With Type and Name fields, choose the operand you want to use instead.

– To search for an instruction, click Instruction. Click Action or Condition, and choose the instruction you want to replace from the Find drop-down list. In the Replace With drop-down list, choose the instruction you want to use instead.

– To search for a substring within tag names, click Tag. In the “Find what” text box under Substrings, enter the substring you want to replace. In the “Replace with” text box, enter the replacement text. For example, if you have several tag names that contain the substring, “Generic,” such as nGenericCount, fGenericTemperature, and diGenericInput, you could replace “Generic” with “Station1,” and the tagnames would become nStation1Count, fStation1Temperature, and diStation1Input.

4. Click Find Next.

When the first occurrence of the operand or instruction is found, the Instructions dialog box it appears in is displayed.

5. To replace this occurrence, click Replace. To skip it and find the next one, click Find Next.

If you are replacing operands, you can replace all occurrences at once by clicking Replace All. If you are replacing instructions, you must verify each one.

Point name



6. If the Edit Instructions dialog box appears, make any necessary changes and click OK to save them before moving on.

7. When replacements are finished, close the Find and Replace dialog box.

Legacy OptionsBecause our focus in PAC Project is on the SNAP PAC System, PAC Control initially shows only SNAP PAC I/O units and the commands used with them. When you’re using the SNAP PAC system only, hiding legacy I/O units and commands makes it simpler and less confusing to build your strategy. However, the legacy capabilities are still there and can be made visible in a specific strategy as needed.

NOTE: If you enable legacy I/O capabilities in PAC Control, see the legacy versions of the PAC control guides for information on how to use them: forms 1710 and 1711.

Existing StrategiesWhen you open an existing ioControl strategy in PAC Control, either Basic or Professional, PAC Control will automatically show the I/O units and commands appropriate to that strategy. For example, if you have been using SNAP Ultimate I/O, SNAP Ultimate I/O units will be visible in the strategy. In addition, commands used with SNAP Ultimate I/O but now deprecated because they are not needed with SNAP PACs—such as High-Density Digital commands—will also be available.

Similarly, if you open an existing strategy that contains mistic serial I/O units, all the mistic I/O unit types and commands—such as event/reaction and mistic PID commands—will automatically be shown.

New StrategiesWhen you create a new strategy in PAC Control, either Basic or Professional, the strategy will show only the SNAP PAC System. This means:

• When you use a command such as Get I/O Unit as Binary Value, the only I/O units shown for Argument 1 will be SNAP PAC I/O units (SNAP-PAC-R1, SNAP-PAC-R2, SNAP-PAC-EB1, SNAP-PAC-EB2, SNAP-PAC-SB1, and SNAP-PAC-SB2).

• Commands that are used only with legacy hardware—such as Enable Communication to Mistic PID Loop or Clear HDD Module Off-Latches—won’t be listed.

Since some Opto 22 customers work with multiple systems, legacy options can be set individually for each strategy or subroutine. If you are using legacy hardware, you can choose the options that apply to each strategy you’re working with, without affecting other strategies.

IMPORTANT: Once you have enabled a legacy option for a specific strategy or subroutine, you cannot disable it later for the same strategy or subroutine.

LEGACY OPTIONS


Enabling Legacy OptionsHere’s how to set legacy options:1. In PAC Control, open the strategy or subroutine for which you want to change options. 2. Choose File > Strategy Options. Click the Legacy tab.

Depending on the hardware you’re using, you can set one or more of the following options:

– Enable Ethernet, Ultimate, and Simple I/O units and commands (see page 208).

– Enable high-density digital commands (see page 208).

– Enable mistic I/O units and commands (PAC Control Pro only; see page 209).3. Click the option you want to enable. At the confirmation dialog box, make sure it is

correct, and then click Yes. Repeat to enable other options.

The options are changed for the strategy or subroutine.

Enable Ethernet, Ultimate, and Simple I/O Units and Commands

If you’re using any of the I/O unit types shown in the following table, you should enable Ethernet, Ultimate, and Simple I/O units and commands. When you do, both the I/O unit types and the commands shown in the table will become available in the strategy.

Enable High-Density Digital Module Commands

All SNAP high-density digital modules are fully supported by the SNAP PAC System using regular digital point commands. However, three of our older HDD modules can also be used with analog-capable SNAP Ultimate, SNAP Ethernet, and SNAP Simple I/O units, if you use the older “deprecated” HDD commands.

I/O Unit Types Commands

SNAP-ENET-D64SNAP-B3000-ENET, SNAP-ENET-RTCSNAP-UP1-D64SNAP-UP1-ADSSNAP-UP1-M64SNAP-ENET-S64

IVAL Set Digital-64 I/O Unit from MOMO Masks [DEPRECATED]IVAL Set Mixed 64 I/O Unit from MOMO Masks [DEPRECATED]IVAL Set Mixed I/O Unit from MOMO Masks [DEPRECATED]IVAL Set Simple 64 I/O Unit from MOMO Masks [DEPRECATED]Set Digital-64 I/O Unit from MOMO Masks [DEPRECATED]Set Mixed 64 I/O Unit from MOMO Masks [DEPRECATED]Set Mixed I/O Unit from MOMO Masks [DEPRECATED]Set Simple 64 I/O Unit from MOMO Masks [DEPRECATED]



If you are using SNAP-ODC-32-SNK, SNAP-ODC-32-SRC, or SNAP-IDC-32 HDD modules with these older I/O units, you should enable High Density Digital module commands. When you do, the following commands become available in the strategy:

Enable mistic I/O Units and Commands

If you’re using legacy mistic hardware with a SNAP PAC S-series controller and PAC Control Professional, you should enable mistic I/O units and commands. When you do, the following types and commands will become available in the strategy:

Commands

Clear HDD Module Off-LatchesClear HDD Module On-LatchesGet & Clear All HDD Module Off-LatchesGet & Clear All HDD Module On-LatchesGet & Clear HDD Module CounterGet & Clear HDD Module CountersGet & Clear HDD Module Off-LatchesGet & Clear HDD Module On-LatchesGet All HDD Module Off-Latches

Get All HDD Module On-LatchesGet All HDD Module StatesGet HDD Module CountersGet HDD Module Off-LatchesGet HDD Module On-LatchesGet HDD Module StatesSet HDD Module from MOMO MasksTurn Off HDD Module PointTurn On HDD Module Point

I/O Unit Types Other Types

G4D16RG4D32RSG4A8R, G4RAXB200B3000 (Digital)B3000 (Analog)B100SNAP-BRS

Mistic PID LoopDigital Event/ReactionAnalog Event/ReactionEvent/Reaction Group

LEGACY OPTIONS


Commands

Clamp Mistic PID OutputClamp Mistic PID SetpointClear All Event LatchesClear Event LatchConvert Mistic I/O Hex String to FloatConvert Number to Mistic I/O Hex StringDisable Communication to Event/ReactionDisable Communication to Mistic PID LoopDisable Event/Reaction GroupDisable Mistic PID Output Tracking in Manual ModeDisable Mistic PID OutputDisable Mistic PID Setpoint Tracking in Manual ModeDisable Scanning for All EventsDisable Scanning for EventDisable Scanning of Event/Reaction GroupEnable Communication to Event/ReactionEnable Communication to Mistic PID LoopEnable Event/Reaction GroupEnable Mistic PID Output Tracking in Manual ModeEnable Mistic PID OutputEnable Mistic PID Setpoint Tracking in Manual ModeEnable Scanning for All EventsEnable Scanning for EventEnable Scanning of Event/Reaction GroupEvent Occurred?Event Occurring?Event Scanning Disabled?Event Scanning Enabled?Event/Reaction Communication Enabled?Event/Reaction Group Communication Enabled?Get Analog Filtered ValueGet Analog Square Root Filtered ValueGet Analog Square Root ValueGet Analog Totalizer ValueGet & Clear Analog Filtered ValueGet & Clear Analog Totalizer ValueGet & Clear Event LatchesGet & Restart Off-Time TotalizerGet & Restart On-Time TotalizerGet & Restart Period

Get Event LatchesGet FrequencyGet Mistic PID Control WordGet Mistic PID D TermGet Mistic PID I TermGet Mistic PID InputGet Mistic PID ModeGet Mistic PID Output Rate of ChangeGet Mistic PID OutputGet Mistic PID P TermGet Mistic PID Scan RateGet Mistic PID SetpointGet Off-Time TotalizerGet On-Time TotalizerGet PeriodGet Period Measurement Complete StatusIVAL Set Analog Filtered ValueIVAL Set Digital Binary [DEPRECATED]IVAL Set FrequencyIVAL Set Mistic PID Control WordIVAL Set Mistic PID Process TermIVAL Set Off-TotalizerIVAL Set On-TotalizerIVAL Set PeriodMistic PID Loop Communication Enabled?Read Event/Reaction Hold BufferSet Analog Totalizer RateSet Digital I/O Unit from MOMO Masks [DEPRECATED]Set Mistic PID Control WordSet Mistic PID D TermSet Mistic PID I TermSet Mistic PID InputSet Mistic PID Mode to AutoSet Mistic PID Mode to ManualSet Mistic PID Output Rate of ChangeSet Mistic PID P TermSet Mistic PID Scan RateSet Mistic PID SetpointTransmit/Receive Mistic I/O Hex String


8: 8: Working with FlowchartsChapter 8

8: Working with Flowcharts

IntroductionThis chapter shows you how to work with flowcharts, the building blocks of your strategy. When you create a new strategy, one chart is created for you: the Powerup Chart. You must create all the other charts to do the work of the strategy.

In this ChapterCreating a New Chart ............................................. 211Working with Chart Elements............................. 213Opening, Saving, and Closing Charts .............. 224Copying, Renaming, and Deleting Charts ..... 225Printing Charts ........................................................... 226Exporting and Importing Charts........................ 227

Creating a New Chart1. With your strategy open and in Configure mode, select Chart > New, or right-click the

Charts folder on the Strategy Tree and select New from the pop-up menu.

The Add New Chart dialog box appears.

CREATING A NEW CHART


2. Enter a name for the new chart.

The name must start with a letter, but may also include numbers and underscores. If you type spaces, they are converted to underscores. All other characters are ignored.

3. (Optional) Type a description.4. Click OK.

The new chart is listed on the Strategy Tree under the Charts folder, and the new chart window appears. Block 0, the starting block, is shown automatically. No matter how many other blocks you add or where you place them, block 0 is always the first block to be executed in the chart.

NOTE: Because chart windows show a small portion of a potentially large chart, a small movement with the scroll bar can mean a big change in what you see. If you lose your flowchart in the window, select View > Center on Block and choose the block you want to see in the middle of the screen.

CHAPTER 8: WORKING WITH FLOWCHARTS


Working with Chart Elements

Chart ComponentsCharts can contain five kinds of flowchart blocks, lines connecting the blocks, and text.

Action Blocks are rectangles that contain one or more commands (instructions) that do the work of the strategy, such as turning things on or off, setting variables, and so on. See “9: Using Variables and Commands” for more information. Action blocks can have more than one entrance but only one exit.

Condition Blocks are diamonds containing questions that control the logical flow of a strategy. Condition blocks can have many entrances, but only two exits: True and False.

OptoScript Blocks are hexagons containing OptoScript code, a procedural language you may want to use to simplify certain tasks. See “11: Using OptoScript” for more information. OptoScript blocks can have more than one entrance but only one exit.

Continue Blocks are ovals that contain no commands, but simply route chart logic to a new location, such as to the top of a chart. These blocks help keep charts neat by avoiding awkward connections between two blocks that are far apart.

Sync Blocks are used in charts that control systems with controller redundancy. When a sync block is encountered, the redundant controllers are synchronized. For more information, see form 1831, the SNAP PAC Redundancy Option User’s Guide.

Connections are lines with arrows that connect one block to the next, directing the flow of strategy logic.

Text explains the chart’s purpose and elements for anyone who needs to understand them later.

Using the Drawing Toolbar

The drawing toolbar includes tools for each of the elements plus a Select tool, or pointer, for manipulating elements:

Action blockOptoScript block

Continue block

SelectConnect

Text

Condition block

WORKING WITH CHART ELEMENTS


Changing the Appearance of Elements in a Chart WindowYou can change the background appearance of charts or subroutines, the color and size of blocks and text, and the color of connection lines. Depending on the scope you want to affect, you can change these window properties at three levels:

• Across PAC Control—to change the appearance of all new charts in all new strategies, and all new subroutines.

• Across a strategy—to change the appearance of all new charts in the open strategy.

• For the open chart or subroutine—to change the appearance of all new elements in the open chart or subroutine window.

IMPORTANT: Note that most changes affect only new charts and their elements. Existing charts, subroutines, and elements are not changed. To avoid having to go back and change each item individually, make sure you set the defaults the way you want them before you create new charts. Once you have changed the defaults, see “Changing Existing Elements to Match New Defaults” on page 216 to change existing elements to match the new defaults.

To change the appearance of charts and elements, follow these steps:1. Choose one of the following, depending on the scope you want to change:

– To change all new charts in all new strategies and all new subroutines, choose Configure > Default Properties to open the Configure PAC Control Default Properties dialog box.

– To change all new charts in the open strategy only, choose File > Strategy Properties to open the Configure Strategy Properties dialog box.

– To change new elements in the open chart or subroutine only, choose Chart > Properties or Subroutine > Properties to open the Configure Chart Properties or Configure Subroutine Properties dialog box.

The dialog box that opens looks like this, except that its title may be different.

2. Complete the fields as described in “Configure Chart Properties Dialog Box” below.3. When you have made all the changes, click OK.



Configure Chart Properties Dialog Box

A—Flowchart Properties. Specify general chart display in this area. To apply these changes to existing charts as well as to new ones, click All charts in D.

• To change the chart background color from the default of white, click the Background Color box. Choose a new color from the Color dialog box.

• To change the chart’s grid color from the default of black, click the Grid Color box.

• The grid and block ID numbers are displayed by default. To remove them, click Display Grid or Display Block ID’s to remove the check mark.

• To enable or disable smooth scrolling in a flowchart, click Smooth Scrolling; this option is disabled by default.

B—Action Block Parameters. Define the appearance of action blocks, condition blocks, OptoScript blocks, and continue blocks in this area. These changes affect new blocks only, not existing blocks. (To change existing blocks, see “Changing Existing Elements to Match New Defaults” below.)

• In the Width and Height fields, type the block size in pixels. For action and continue blocks, the default width is 96 and the default height is 48; the minimum parameters are 48 (width) and 32 (height). For condition blocks, the default height is 64. (Note that the numbers you enter are rounded down to be evenly divisible by 16; for example, if you enter 81, click OK and then reopen the dialog box, the parameter reads 80.)

• To change the color of the blocks from the default, click the Color box.

A

B

C

D

E



• To change block name text formatting, click the Font box. In the Font dialog box, change the font, font style, size, effects, and color. The default font is black 10-point Arial bold.

• To change text alignment, right-click the Font box and choose left, center, or right from the pop-up menu.

• To change the color of connection lines, click a Connection line at the far right. Choose the new color from the Color dialog box.

C—Text. Define width, height, and font of text blocks that appear as comments in a chart or subroutine. Default width is 192; default height is 128; the minimum for both is 16. The default font is black 10-point Arial bold.

D—Also Apply To. To expand the scope of the changes you’ve made, click these boxes. Click PAC Control to apply the changes to all new strategies and subroutines in PAC Control. Click Strategy to apply the changes to all new charts in the current strategy. Click All Charts to apply the changes to all new charts and all new graphic elements added to the current strategy.

Depending on which dialog box you are in and what is currently open, one or more of these options may be grayed out. For example, if you are in the Configure PAC Control Default Properties dialog box, it is assumed that the changes are to be applied throughout PAC Control, and that option is therefore grayed out.

E—Reset All. To reset all parameters and options to their factory default settings, click Reset All.

Changing Existing Elements to Match New Defaults

Once you have changed the defaults for the way elements appear in a chart, you can update existing blocks, connections, and text to match.

CAUTION: When you update existing objects to match, you cannot undo the update.

1. Right-click on an empty space in the chart whose elements you want to change. Choose Select from the pop-up menu. From the sub-menu, choose the item type you want.

For example, to select all action blocks, choose Select > Action Blocks.

2. Right-click again in the chart, and choose Properties > Copy from Default from the pop-up menu.

The color, size, and font of all selected items change to match the flowchart defaults.

Drawing BlocksAction, condition, OptoScript, and continue blocks are all drawn the same way.



1. With the chart open and the strategy in Configure or Online mode, click the tool you want to use.

for an action block

for a condition block

for an OptoScript block for a continue block.

As you move the mouse into the window, you see an outline representing the block.

2. Click where you want to place the block.

The new block appears.

3. Click in another location to place other blocks of the same type. When you have finished using the tool, click the right mouse button, click another tool in the toolbar, or press ESC.

Naming Blocks1. With the chart open and the strategy in Configure or Online mode, click the Select tool

and click the block to select it.2. Right-click the block and choose Name from the pop-up menu.

3. In the Name Block dialog box, type the name and click OK.



Renaming Blocks

1. With the chart open and the strategy in Configure or Online mode, click the Select tool and click the block to select it.

2. Right-click the block and choose Name from the pop-up menu.3. In the Name Block dialog box, change the name. Click OK.

Connecting BlocksTo connect blocks, start with the chart open and the strategy in Configure or Online mode. Remember that action blocks and OptoScript blocks have only one exit, and condition blocks have two.

Action Blocks and OptoScript Blocks

1. To connect an action block or an OptoScript block to the next block in a program sequence, click the Connect tool .

2. First click the source block and then click the destination block.

Although you can click anywhere inside the blocks to make a connection, the connection is attached at the side closest to where you clicked. In the figure below, Block 0 is the source block and Block 1 is the destination block:

To keep your charts neat, try to draw the most direct connections possible. To do so, after clicking the source block, move your cursor out of the block at a point closest to its destination.

3. To create a bend or elbow in a connection, click wherever you want the bend while drawing the connection.



For example, to draw the connection in the following figure, we selected the Connect tool, clicked Block 0, moved the cursor out of the block to the right, clicked at point A, clicked again at point B, and then clicked the right side of Block 1:

4. While you’re still drawing a line, to delete an elbow you don’t want, click the right mouse button once to undo it.

If you created several elbows, you can eliminate them in reverse order with repeated right mouse clicks. If no more elbows remain and you right-click again, you delete the connection. Once you have completed a connection, however, you cannot undo it this way.

Condition Blocks

1. To connect a condition block to the next block in a program sequence, click the Connect tool .

2. Click the source block.

3. Indicate whether you are drawing the True connection or the False connection, and then click OK.

4. Click the destination block you chose (True or False).

The connection is labeled T or F depending on its type.

5. Draw another connection to the second destination block.

It is labeled the opposite exit type.



For example, the following figure shows the True and False connections from the condition block, Block 1. If the conditions in Block 1 are true, Block 2 is executed next. If the conditions in Block 1 are false, Block 0 is executed next:

Adding TextOne of the best places to put comments about a strategy is directly on its flowcharts. Start with the chart open and the strategy in Configure or Online mode.

1. To add text to a chart, click the Text tool .

When you move the mouse onto the chart, a rectangle representing the text area appears.

2. Click the mouse button and type your comments.

If you type in more text than the text frame holds, it expands in length.

3. When you have finished typing, click anywhere on the chart outside the text frame.

The frame becomes invisible, and only the text appears. To change the size or shape of the text block, see “Resizing Blocks or Text Blocks” on page 223.

4. Click in another location to create another text frame, or release the tool by right-clicking in the chart or choosing another tool from the toolbar.

Editing Text

1. With the chart open and the strategy in Configure or Online mode, click the Select tool .

2. Double-click the text block you want to change.

A blinking cursor appears at the beginning of the text.

3. Change the text as needed.



You can use any standard Windows CTRL key combinations when editing, including CTRL+arrow keys and CTRL+HOME or END for navigation. You can also use CTRL+X (cut), CTRL+C (copy), and CTRL+V (paste).

4. When you have finished changing text, click outside the text frame.

The text block stays the same width but changes length to accommodate additional or deleted text. To change the size or shape of the text block, see “Resizing Blocks or Text Blocks” on page 223.

Selecting ElementsBefore you can manipulate most elements, you need to select them. Start with the chart open and the strategy in Configure or Online mode.1. Click the Select tool .2. To select an action, OptoScript, condition, continue, or text block, click the block.

Handles appear around the block:

3. To select a connection, click it.

Handles appear at the elbows and end points of the connection:

4. To select all connections entering or exiting a block, click the block, click the right mouse button, and choose Select Connections from the pop-up menu.

5. To select more than one element, do one of the following:

– Select the first element, hold down the SHIFT key, and select additional elements.

– Click and drag the mouse to draw a rectangle completely around the elements you want to select.

– To select all items of the same type, right-click anywhere in the window and choose Select from the pop-up menu. From the sub-menu, choose the item type you want.

Handles

Handles



Moving Elements1. With the chart open and the strategy in Configure or Online mode, click the Select tool

.2. To move any action, OptoScript, condition, continue, or text block, click it. Then click

and hold the mouse button anywhere on the selected item except on its handles, and drag it to the position you want.

You can also use the arrow keys on your keyboard to move a block in any direction. Note that when you move a block, any connections attached to it also move.

3. To move a connection, click it. Then click and drag any handle in any direction.

You can also move an end point from one block to another, as long as the result is a valid connection. A disallowed move is ignored.

4. To move several elements at once, select them, and then click and drag them.

If elements end up stacked on top of each other, you may need to change their z-order before you can move them. See the following section.

Moving Elements in Front of or Behind Other Elements (Changing Z-Order)

If elements are stacked on top of each other, you can select only the one in front. To change their position (z-order), follow these steps: 1. Click the element to select it.2. Right-click the element. From the pop-up menu, choose Z-order. From the sub-menu,

choose the action you want to take:

– Bring Forward—moves the element one position closer to the front.

– Bring To Front—moves it all the way to the front.

– Send Backward—moves the element one position closer to the back.

– Send To Back—moves it all the way to the back.

Cutting, Copying, and Pasting ElementsYou can cut, copy, and paste most chart or subroutine elements. Cut or copied elements are placed on the Windows Clipboard, and they can be pasted in the same chart or subroutine, in a different chart or subroutine, or in a different strategy.

A connection can be cut or copied, but it cannot be pasted unless its original source and destination blocks have also been pasted. Block 0 cannot be cut.1. With the chart open and the strategy in Configure or Online mode, click the Select tool

. 2. To cut or copy element(s), click them. Press CTRL+X to cut or CTRL+C to copy.

You can also select the element(s) and then choose Edit > Cut or Edit > Copy, or click the right mouse button and choose Cut or Copy from the pop-up menu.



3. To paste blocks, press CTRL+V, select Edit > Paste, or right-click anywhere on a chart and select Paste from the pop-up menu.

Text blocks are pasted immediately. For action, condition, or continue blocks, a message appears asking if you want to keep the original name of the block being pasted.

If you paste to a different strategy or to a subroutine, PAC Control checks the referenced variables to make sure they match. Variables that do not exist are created. Variables that exist but are different—for example, a table with the same name but a different table length—are noted in a log file that appears when the paste is complete.

Deleting Elements1. Make sure the chart is open and the strategy is in Configure or Online mode.2. Click the Select tool . Click the element(s) to select them.

CAUTION: Make sure you have selected the element you want. You cannot undo a deletion!

3. Press DELETE.

You can also select the element(s), right-click them, and select Delete from the pop-up menu. Block 0 cannot be deleted.

Changing Element Color and SizeYou can change the colors and sizes of blocks, connections, and text in your chart. To change one element (for example, the color of one block), use the steps in this section. To change more than one at a time, see “Changing the Appearance of Elements in a Chart Window” on page 214.

Start with the chart open and the strategy in Configure or Online mode.

Resizing Blocks or Text Blocks

1. Click the Select tool and click the block to select it. 2. Click one of the handles, then drag it in the direction you want. To resize horizontally

and vertically at the same time, drag a corner handle.

Changing Block Colors

1. Click the Select tool and click the block to select it. 2. Right-click the block and choose Color from the pop-up menu.3. Pick the color you want and click OK.

Changing Text

You can change the size, font, font style, or color of the text in any block.1. Click the Select tool and click the block to select it.

OPENING, SAVING, AND CLOSING CHARTS


2. Right-click the block and choose Font from the pop-up menu.3. In the Font dialog box, make the changes you want. Click OK.4. To change whether text appears at the left, the center, or the right of a block, select the

block and click the right mouse button. From the pop-up menu, choose Justify; from the sub-menu, choose Left, Center, or Right.

Changing an Element Back to the Defaults

1. Select the item and click the right mouse button. 2. From the pop-up menu, choose Properties. From the sub-menu, choose Copy from

Default.

To change defaults, see “Changing the Appearance of Elements in a Chart Window” on page 214.

Opening, Saving, and Closing Charts

Opening a ChartMake sure the strategy is open. In the Strategy Tree, double-click the chart you want to open.

You can also open a chart by selecting Chart > Open, and then double-clicking the chart name in the Open Chart dialog box, which lists all charts that are not currently open.

If a chart is open but not visible on the screen, click the chart’s name tab at the bottom of the window to make it visible.

Saving a Chart1. Make sure the chart is open and is the active window.2. From the Chart menu, choose Save.

Charts are automatically saved when you choose File > Save All. If you choose File > Save Strategy or click the Save Strategy button on the toolbar, you can choose which charts to save in the Save Strategy dialog box.

Closing a ChartTo close a chart, click the close box in the upper-right corner of the chart’s window (not the PAC Control window). You can also close a chart by pressing CTRL+F4 when the chart window is active. If you have made changes to the chart, you are prompted to save them.



Copying, Renaming, and Deleting Charts

Copying a ChartIf an existing chart is similar to one you want to create, it is easier to copy it than to create a new one from scratch. To copy a chart in the same strategy, follow the steps in this section. To copy a chart to another strategy, see “Exporting and Importing Charts” on page 227.1. With the strategy open and in Configure mode, select Chart > Copy.

The Copy Chart dialog box appears.

2. In the From field, choose the chart you want to copy from the drop-down list. 3. In the To field, enter a name for the new chart.

The name must start with a letter and include only letters, numbers, or underscores. (Spaces are converted to underscores).

4. (Optional) Enter a description for the new chart.5. Click OK.

The new chart is created and appears as the active window on the screen.

Renaming a Chart1. Make sure the strategy is in Configure mode and that the chart you want to rename is

the active window.2. From the Chart menu, choose Rename.

PRINTING CHARTS


3. Enter a new name and description (optional). Click OK.

The chart is renamed.

Deleting a ChartYou can delete any charts except for the Powerup chart. However, you cannot delete a chart if it is called or used by another chart in your strategy.1. Make sure the strategy is open and in Configure mode.2. In the Strategy Tree, right-click the name of the chart you want to delete and choose

Delete from the pop-up menu. Or, if the chart is the active window, choose Chart > Delete.

3. At the confirmation message, make sure you are deleting the correct chart.

CAUTION: You cannot undo a deletion!

4. Click Yes to delete the chart.

The chart window disappears (if it was open), the chart is removed from the Strategy Tree, and the strategy is saved.

Printing ChartsYou can print any flowchart. To print a chart as it appears on the screen, see “Printing Chart or Subroutine Graphics” on page 194. To print commands (instructions) for the chart, see “Viewing and Printing Strategy or Subroutine Commands” on page 197.



Exporting and Importing ChartsTo copy a chart to another strategy, you must export it as a PAC Control chart export file (.cxf file) and then import it into the strategy where you want it.

Exporting a Chart1. With the strategy open and in Configure or Online mode, choose Chart > Export.

The Export Chart dialog box appears.

2. In the From section of the dialog box, select the chart to be exported from the Name drop-down list.

3. In the To section of the dialog box, click Select.

4. Navigate to where you want the exported chart file to be saved. In the File name field, enter a name for the exported chart. Click Save.

You return to the Export Chart dialog box, which now shows the path and file name in the To section.

5. (Optional) Enter a description for the new chart.

EXPORTING AND IMPORTING CHARTS


6. Click OK.

The exported chart is saved. You can import it into any PAC Control strategy. See the next section for information on importing charts.

Importing a Chart1. With the strategy open and in Configure mode, choose Chart > Import.

The Automatic Chart Import dialog box appears.

2. At the top of the dialog box, click Create new chart or Replace existing chart.

CAUTION: If you choose Replace existing chart, the old chart will be completely overwritten with the chart you are importing.

3. Click Select. Navigate to the exported chart. Click OK.4. In the To section of the dialog box, enter a name for the new chart. If you wish, enter a

description. If you are replacing an existing chart, choose the chart to be replaced. Click OK.

The chart is imported. A Chart Import Report window shows you how the tags in the chart match with those already in the strategy. Any tags from the chart that do not already exist in the strategy are created and added.


9: 9: Using Variables and CommandsChapter 9

9: Using Variables and Commands

IntroductionThis chapter discusses the seven types of variables used in PAC Control: numeric, string, pointer, numeric table, pointer table, string table, and communication handle variables.

This chapter also shows you how to use the commands, or instructions, in PAC Control and discusses the mechanics of adding commands to your strategy flowcharts. For command information to help you program your strategy effectively, see Chapter 10. To find out how to use commands in OptoScript code, see Chapter 11. For a list of all standard PAC Control commands and their OptoScript equivalents, see Appendix E.

In this ChapterAbout Variables ......................................................... 229Variables in PAC Control......................................... 231Adding Variables ....................................................... 233Adding Tables............................................................. 237Changing a Configured Variable........................ 241Viewing Variables in Debug Mode ................... 242Adding Commands ................................................. 247Changing a Command........................................... 251Deleting a Command ............................................. 251Cutting or Copying a Command ....................... 252Configuring a Continue Block............................. 253Viewing and Printing Chart Instructions ........ 254

About VariablesAs Chapter 2 mentions, variables store pieces of information in a strategy. You create a variable for each piece of information in your control process that must be acted upon. These pieces of information might include the name of a chart, the on or off state of a switch, communication parameters for a peer on the network, or a table that holds a series of numbers.

ABOUT VARIABLES


Each variable has a name and a value. You assign the variable’s name in plain English, so you know what it is. The variable’s value is the current information it represents. As a strategy runs, the variable’s name remains the same, but its value may change. For example, the name of the variable Oven_Temperature stays the same, but its value (the temperature of the oven) may change several times while the strategy is running.

To illustrate variables, suppose you are regulating the amount of water in a tank. You must keep the tank filled beyond a minimum level, but you cannot let it get too full.

You’ve already configured the I/O points:

• Level_Meter is an analog input point that registers the quantity of water in the tank.

• Pump_1 is a digital output point that turns the pump on or off.

• Drain_1 is a digital output point that opens or closes the drain.

Next, you configure variables as places to hold information that these I/O points must work with:

• To avoid constantly polling Level_Meter to find out the quantity of water in the tank, you create a variable called Tank_Level_Reading in which to store the level. The input point Level_Meter is periodically checked and the value of Tank_Level_Reading updated.

• To establish the maximum and minimum levels, you create variables called Tank_Max_Level and Tank_Min_Level. The value in Tank_Level_Reading can be compared to the values in these two variables to determine whether the pump should be turned on or off, or the drain opened or closed, to maintain the proper level. (You could create constant values, called literals, for the minimum and maximum levels, but creating them as variables lets you change their values in Debug mode.)

Types of Data in a VariableA variable stores one of six types of data: floating point, integer, timer, string, pointer, or communication handle. When you create the variable, you designate the type of data it contains. It is always best to choose the most appropriate data type for the information you are storing. PAC Control can store an integer in a floating point variable, but it has to convert the data first. Unnecessary data conversions take up processor time.

• Numeric data stores numbers and can be one of the following types:

– A floating point (or float) is a numeric value that contains a decimal point, such as 3.14159, 1.0, or 1,234.2. A good example of a float variable is one that stores readings from an analog input such as a thermocouple. PAC Control uses IEEE single-precision floats with rounding errors of no more than one part per million.

Pump_1

Drain_1

Level_Meter

(Tank)

CHAPTER 9: USING VARIABLES AND COMMANDS


– An integer is a whole number with no fractional part. Examples of integer values are -1, 0, 1, 999, or -4,568. The state of a switch, for example, could be stored in an integer variable as 1 (on) or 0 (off ). Most integers used in PAC Control are 32-bit signed integers, which can range from -2,147,483,648 to 2,147,483,647. These 32-bit integers should be used for general integer use, such as status variables, mathematics, and indexes. . 64-bit integers address the entire I/O unit at once but are slower than integer 32 commands.

– A timer stores elapsed time in units of seconds with resolution in milliseconds. Up Timers count up from zero, and Down Timers start from a value you set and count down to zero. Timers can range from 0.001 to 4.611686 x 1015.

• A string stores text and any combination of ASCII characters, including control codes and extended characters. For instance, a string variable might be used to send information to a display for an operator to see. A string variable is also used to set parameters for peer-to-peer communication. When defining most string variables, you must specify the width of the string. The width is the maximum number of characters that the variable may hold.

A string variable can contain numeric characters, but they no longer act as numbers. To use them in calculations, you must convert them into floating point or integer numbers. Conversely, a numeric value to be displayed on a screen must first be converted into a string.

• A pointer does not store the value of a variable; instead, it stores the memory address of a variable or some other PAC Control item, such as a chart or an I/O point. You can perform any operation on the pointer that you could perform on the object the pointer points to. Pointers are an advanced programming feature and are very powerful, but they also complicate programming and debugging.

• A communication handle stores information used to communicate with other entities, for example other devices on the network or files that store data. The communication handle’s value is a string containing the parameters needed to make a connection with a specific entity. For outgoing Ethernet communication, for example, these parameters usually include the protocol, the IP address of the device you are communicating with, and the port number used on the device.

After the initial connection is made, the communication handle is referenced during communication with the entity, and then used to close communication.

Variables in PAC ControlIn PAC Control there are seven types of variables:

• numeric

• numeric table

• string

• string table

ABOUT VARIABLES


• pointer

• pointer table

• communication handle

Numeric, string, and pointer variables contain individual pieces of data. Numeric table, string table, and pointer table variables contain several pieces of related data in the form of a table. Communication handle variables contain parameters used by PAC Control for communicating with other devices and files.

Table Variables

In a table variable, the variable name represents a group of values, not just one. Table variables are one-dimensional arrays, which means that each table is like a numbered list of values. You refer to each item in the list by its number, or index. Indexes start at 0, not at 1. Here are two table examples:

In a float table, values are floating point numbers:

In a string table, values are strings:

When you define a table, you must specify its length, which is how many values the table can store. The length of a table is NOT the value of the last index. Since indexes start at 0, a table with a length of 100 contains indexes 0 through 99. Table length is limited only by the amount of memory in the control engine. (For more information on the available memory, see “If You Have Memory Problems” on page 369.)

Numeric tables store either integer values or floating point numbers (but not both in the same table). String tables store strings. Because pointers can point to any data type (for example, an I/O point, a chart, or even another table), pointer tables can store an assortment of data types.

Index Value

0 82.0

1 86.1

2 85.0

3 74.8

4 72.3

5 72.7

Index Value

0 Maria

1 Tom

2 Siu

3 Andre



Persistent DataMost variables can be either global or persistent in scope. Global variables are set to an initial value (which you specify during configuration) either whenever the strategy is run or whenever it is downloaded.

Persistent variables, however, are initialized only when the strategy is first downloaded. The variable’s value is saved in the controller’s memory; it does not change when the strategy is run, stopped, or started, and it does not change if the strategy is changed and downloaded again. A persistent variable’s value remains the same until one of the following events occurs:

• A strategy with a different name is downloaded.

• The RAM memory on the controller is cleared.

• A new firmware kernel is downloaded to the controller.

• The persistent object is changed as follows:

– A persistent table's length (integer, 64-bit integer, float, and string) was modified.

– A persistent string variable's length was modified.

– A persistent string table element's string length was modified.

– A persistent variable's type has changed. For example, a persistent float variable is deleted and a new persistent integer variable is created with the same name.

Persistent data can be very useful in certain situations. For example, suppose you have a PID setpoint that is fine-tuned as your process runs. If the setpoint is configured as persistent, its value won’t be lost if you must re-download the strategy after making a program change.

Pointer variables, pointer tables, and timers are not allowed to be persistent; but all other variables and tables can be. Persistent variables cannot be configured on-the-fly.

LiteralsA literal is used like a variable, but it is constant data that never changes. A literal has no variable name, only a fixed value, which may be a floating point number, an integer, or a string.

If you are using subroutines, see the information on literals in “Data Types for Subroutines” on page 354.

Adding VariablesThis section includes steps for adding numeric, string, pointer, and communication handle variables. (For numeric, string, and pointer tables, see “Adding Tables” on page 237.)1. With the strategy or subroutine open in Configure mode, choose Configure > Variables.

The Configure Variables dialog box opens.

ADDING VARIABLES


This dialog box lists all the variables in the strategy or subroutine that are of the type shown in the Type field. You can sort the data in this dialog by clicking any one of the column header buttons.

2. In the Type drop-down list, choose the type of variable you want to configure.3. If you are adding the variable to a subroutine, select Subroutine in the Scope

drop-down list. 4. To add a new variable, click Add.

The Add Variable dialog box appears.

5. Complete the fields as described in “Add Variable Dialog Box” below.6. Click OK.

The Add Variable dialog box closes and the new variable appears in the Configure Variables dialog box.

Add Variable Dialog Box

This dialog box varies depending on the type of variable.

The figure above shows the Add Variable dialog box as it appears for string variables. Fields are slightly different for other variables.

AB

D

E

F

C

Field at D varies depending on variable type.



A—Name. Enter a name for the variable. The name must start with a letter and may contain letters, numbers, and underscores. (Spaces are converted to underscores.)

B—Description. (Optional) Enter a description of the variable.

C—Type. In the Type drop-down list, select the type of data for the variable. Possible types are shown in the following table. For more information, see “Types of Data in a Variable” on page 230.

D—String Width. This field varies depending on the variable type.

(Table variables only) In the Table Length field, enter an integer between 1 and 1,000,000 representing the number of elements in the table. The greater the number, the more memory required to store the table.

(String variables and string tables only) In the String Width field, enter the maximum number of characters permitted in the string. The number must be an integer between one and 1024. The greater the number, the more memory required to store the string.

(Pointer variables only) From the Pointer to Type drop-down list, select the type the pointer points to. Note that void pointers are not allowed; a pointer must point to a specific type. Also note that you cannot point a pointer to another pointer; PAC Control has only one level of indirection for pointers. If you try to point to a pointer, PAC Control assigns to the new pointer the address of the object being pointed to.

E—Initialization. (For all variables except up timers and down timers)

Select one of the following:

Initialize on Strategy Run: Sets the variable to the initial value (F) each time the strategy is run (either manually from the debugger or automatically via the autorun flag).

Initialize on Strategy Download: Sets the variable to the initial value (F) only when a strategy is downloaded. The variable retains its current value when the strategy is stopped and then run again, either through the debugger or autorun. It also retains its value if power is cycled. Note that this choice means the variable is stored in battery-backed RAM, which is limited in size. To keep a variable’s current value through both power cycles and strategy download,

Variable Possible Data Types

Numeric Integer 32, integer 64, floating point, up or down timer

Numeric table Integer 32, integer 64, or floating point

String String

String table String

Pointer Pointer to any data type

Pointer table Pointer to any data type, and the data type may change over time

Communication handle Communication handle

ADDING VARIABLES


make the variable a persistent variable (see the Persistent option below and “Persistent Data” on page 233). See “If You Have Memory Problems” on page 369.

Persistent: Data in the variable will be persistent. Pointer variables and timers cannot be persistent. For more information, see “Persistent Data” on page 233.

The following table shows how your choices about variable initialization and persistence affect what happens to variables (applies to all variables and tables except up timers and down timers).

F—Initial Value. (For all variables except pointers, up timers, and down timers) Enter the value to which the variable is to be set initially. You can use either decimal or hexadecimal form. If you leave this field blank, the initial value is set to zero.

(For pointer variables only) When you have selected the Pointer to Type, the drop-down list in this field shows all the valid objects for that type that are currently defined in your strategy. Choose one or leave the initial value as NULL. A NULL value means that the pointer is created but does not initially point to anything.

(For communication handles only) Enter a string containing communication parameters in the correct format for the type of communication handle you are using. The type (for example, tcp, ftp, file) must be in lowercase letters, and parameters are separated by colons and commas according to the format required. See “Communication Commands” on page 259 for information and examples.

• If you are talking to a serial module, use the IP address of the brain the module is attached to, and use the serial module’s port number according to its position on the rack, for example: tcp:10.192.55.185:22502. For port numbers, see “Establishing an Ethernet Connection” in form 1191, the SNAP Serial Communication Module User’s Guide. See also, form 1941, TCP and UDP Port Assignments.

• If you are talking to another SNAP PAC brain, be aware of port numbers that are reserved for a specific protocol. For more information, see form 1941, TCP and UDP Port Assignments.

• For other peers on the Ethernet network, be aware of port numbers they may use for specific purposes. Ports 22000 and 22001 are reserved for the control engine. For a list of standard Ethernet port numbers, refer to http://www.iana.org/assignments/port-numbers. See also, Opto 22 form 1941, TCP and UDP Port Assignments.

Variable What happens to the variable’s value when...

Strategy stops, then starts (through debugger or autorun) Power is cycled Same strategy is

downloaded

Variable initialized on strategy run (default) Set to initial value Set to initial value Set to initial value

Variable initialized on strategy download Retains current value Retains current value Set to initial value

Persistent variable Retains current value Retains current value Retains current value



• If you are using the Accept Incoming Communication command to listen for communication requests, leave out the IP address and use the following format: tcp:port

For tables, each value in the table is set to the initial value. If you need to set individual table elements to differing values intially, you can do so in the Powerup chart. If you need to use an initialization file to set values on strategy download, contact Opto 22 Product Support.

Adding Tables See the following topics to add numeric, string, and pointer tables:

• “Adding Table Variables” (below)

• “Setting Initial Values in Variables and Tables During Strategy Download” on page 238

Adding Table Variables1. With the strategy or subroutine open in Configure mode, choose Configure > Variables.

The Configure Variables dialog box opens, listing all variables of one type in the strategy.

2. In the Type drop-down list, choose the type of table variable you want to add.3. If you are adding the table variable to a subroutine, select Subroutine in the Scope

drop-down list.4. To add a new table variable, click Add.

The Add Variable dialog box appears.

SETTING INITIAL VALUES IN VARIABLES AND TABLES DURING STRATEGY DOWNLOAD


The figure above shows the dialog box as it appears for string tables. Fields are slightly different for other table variables.

5. Complete the fields as described in “Add Variable Dialog Box” on page 234.

NOTE: If you need to set individual table elements to differing values initially, you can do so in the Powerup chart. If you need to use an initialization file to initialize the values on strategy download, see the next section, “Setting Initial Values in Variables and Tables During Strategy Download.”

6. To have data in the table be persistent, select Persistent.

Pointer tables cannot be persistent. For more information, see “Persistent Data” on page 233.

7. Click OK.

The Add Variable dialog box closes and the new table variable appears in the Configure Variables dialog box.

Setting Initial Values in Variables and Tables During Strategy Download

When you are adding table variables in PAC Control, you can set all table elements to one initial value in the Add Variables dialog box. If you want to set each individual table element to its own value, however, you need to create an initialization file and download it with your PAC Control strategy.

In addition to setting initial values for table elements, sometimes it is easier to initialize all variables during strategy download using an initialization file.

This section shows you how to create an initialization file and download it with your strategy.



Creating the Initialization File

A sample initialization file, INIT.TXT, is included with PAC Control. You can open this file with a text editor to see the proper syntax for each initialization entry, and then modify it as necessary for your strategy.

IMPORTANT: Every initialization file should include the following line near the top:

""DOWNLOAD_COMPRESSION_OFF

Download compression removes the new lines necessary for string initialization. This line tells PAC Control to turn off download compression so strings can be initialized.

IMPORTANT: Each file must end with a carriage return, and each line within the file must end with a carriage return. If you add comments to the file, they must be preceded by a backslash (\) and a space.

Text Examples

NOTE: Variable names are case-sensitive and can include both upper- and lower-case letters.

Variables Example . To set initial values of 123 for the variable INTEGER_VARIABLE, 456.789 for FLOAT_VARIABLE, “String Variable Test String” for STRING_VARIABLE, and to have pointer PTR_POINTER_VARIABLE point initially to INTEGER_VARIABLE, you would include the following text in the initialization file:123 ^INTEGER_VARIABLE @!456.789 ^FLOAT_VARIABLE @!*STRING_VARIABLE $INNString Variable Test String^INTEGER_VARIABLE MoveToPointer PTR_POINTER_VARIABLE

Integer 32 Table Example. To set initial values of 10, 20, 30, 40, and 50 for elements zero through four of an integer table named My_Int_32_Table, include the following text:10 0 }My_Int_32_Table TABLE! 20 1 }My_Int_32_Table TABLE! 30 2 }My_Int_32_Table TABLE! 40 3 }My_Int_32_Table TABLE! 50 4 }My_Int_32_Table TABLE!

Integer 64 Table Example. To set initial values of 10, 20, 30, 40, and 50 for elements zero through four of an integer table named My_Int_64_Table, include the following text:10.. 0 }My_Int_64_Table 2TABLE!20.. 1 }My_Int_64_Table 2TABLE!30.. 2 }My_Int_64_Table 2TABLE!40.. 3 }My_Int_64_Table 2TABLE!50.. 4 }My_Int_64_Table 2TABLE!

Float Table Example. For a float table, the initial values must include a decimal point. To set initial values of 1.1, 2.2, 3.3, 4.4, and 5.5 for elements zero through four of a float table named My_Float_Table, include the following text: 1.1 0 }My_Float_Table TABLE! 2.2 1 }My_Float_Table TABLE! 3.3 2 }My_Float_Table TABLE!

SETTING INITIAL VALUES IN VARIABLES AND TABLES DURING STRATEGY DOWNLOAD


4.4 3 }My_Float_Table TABLE! 5.5 4 }My_Float_Table TABLE!

String Table Example. To set initial values of “zero”, “one”, “two”, “three”, and “four” for elements 0–4 of a string table named My_String_Table, include the following text. Make sure you turn off download compression and use new lines as shown:0 {My_String_Table $TABLE@ $INN zero 1 {My_String_Table $TABLE@ $INN one 2 {My_String_Table $TABLE@ $INN two 3 {My_String_Table $TABLE@ $INN three4 {My_String_Table $TABLE@ $INN four

Pointer Table Example. Each index in a pointer table points to another item within the strategy, for example an I/O point, a variable, or a chart. Setting initial values for pointer tables means designating the items the pointer table initially points to. For example, you would include the following text to have a pointer table named My_Ptr_Table initially point to Oven_Temperature (a variable), Alarm_Handler (a chart), Thermocouple (an analog input), Fuel_Pump (an analog output), and Fan_1 (a digital output):^Oven_Temperature 0 PTBL_My_Ptr_Table TABLE! &Alarm_Handler 1 PTBL_My_Ptr_Table TABLE! ~Thermocouple 2 PTBL_My_Ptr_Table TABLE! ~Fuel_Pump 3 PTBL_My_Ptr_Table TABLE! ~Fan_1 4 PTBL_My_Ptr_Table TABLE!

Special Characters in the Initialization File. Note that the initial character on each line of the initialization file is a special character that identifies the object type. Possible characters include the following:

Saving the Initialization File. When you have finished modifying the file, save it as a text file (.txt file extension) to your strategy directory. You can name the file anything you like. (You can also save it to any directory you like, but it is good practice to save each initialization file to the directory of the strategy that references it.)

Downloading the Initialization File

To use the file, you need to download it with your strategy.

Character Object Type Character Object Type

^ float, integer, or timer } float table or

integer table

* string { string table

PTR_ pointer variable PTBL_ pointer table

~ I/O point % I/O unit

& chart



1. With the strategy open in Configure or Online mode, choose Configure > Control Engines, or double-click the control engine’s name.

2. Highlight the control engine and click the Download Options button.

The Download Options dialog box appears. The initialization file must be downloaded immediately after your strategy is downloaded.

3. Click Add. 4. Navigate to the initialization file you created. Double-click the file name.

The file appears in the Download Options dialog box.

5. Click OK.

The initialization file sets values for the variables and table elements immediately after your next full strategy download.

IMPORTANT: When you create each variable in the strategy, you must check “Initialize on Strategy Download” in the Add Variable dialog box.

Since download options are specific to each control engine, make sure you set the initialization file as a download option for every control engine on which the strategy will run. Because control engines have separate initialization files, you can use the same master strategy for two or more control engines and configure differences in variables by customizing the initialization files.

Changing a Configured VariableYou can change a variable, but you cannot change a variable’s type.1. To change a configured variable, make sure the strategy or subroutine is open and in

Configure or Online mode.2. If you are working in a strategy, on the Strategy Tree, expand the Variables folder until

you see the name of the variable you want to change. Double-click its name to open the Edit Variable dialog box.

DELETING A VARIABLE


3. If you are working in a subroutine, choose Configure > Variables. In the Configure Variables dialog box, double-click the name of the variable you want to change.

4. In the Edit Variable dialog box, make the necessary changes and click OK.

If you need help, see “Adding Variables” on page 233 or “Adding Tables” on page 237.

You can also change a variable from the Configure Variables dialog box by double-clicking the variable’s name or by highlighting it and clicking Modify.

Deleting a VariableYou cannot delete a variable that is referenced within the strategy or subroutine. Be careful when deleting variables, since you cannot undo a deletion. 1. Make sure the strategy is open and in Configure mode.2. On the Strategy Tree, expand the Variables folder until you see the name of the variable

you want to change. Right-click the name and choose Delete from the pop-up menu.

The variable is deleted.

You can also delete a variable from the Configure Variables dialog box by highlighting the variable’s name and clicking Delete.

Viewing Variables in Debug ModeWhile the strategy is running in Debug mode, you can view its variables and modify the value of a variable or of entries in a table. You can also view several variables at once—as well as other strategy elements—by putting them into a watch window.

Viewing Numeric, String, and Communication Handle Variables1. Make sure the strategy is running in Debug mode. On the Strategy Tree, double-click

the variable you want to view.

The Inspect Variables dialog box opens. The animated icon at the upper left assures you that the data is fresh. The title bar includes the name of the variable and indicates whether scanning is occurring.

2. To view more options, click the Maximize button.

Maximize button



Scanning stops whenever you click a changeable field. It resumes once you click Apply, another button, or an unchangeable field. If scanning resumes before you click Apply, any changes you made are lost.

If you do not want to change the value of the variable, you can click the Minimize button to shrink the dialog box back to its original size.

3. To view the configuration information about the variable, click More Info.

4. To select the display format, click the button to the right of the Watch button.

A numeric variable can appear as decimal, hexadecimal, or binary. A string variable can appear as ASCII or hexadecimal.

5. To change the value of the variable, type the new value in the Value field and click Apply.

The field turns magenta until you click Apply.

For a string variable, if your change lengthens the string beyond its maximum width, the string is truncated to fit.

For a communication handle variable, changing the value of the variable here has the same effect as using a Set Communication Handle Variable command. If the communication handle is currently open, the value will be changed but will not affect the connection.

6. To monitor the variable in a watch window, click Watch.

Communication handle variables show slightly different fields.

Minimize button

VIEWING VARIABLES IN DEBUG MODE


If you have only one watch window and it is already open, the variable appears immediately in the window for monitoring.

Otherwise, the Add Watch Entry dialog box appears.

7. Check the items you want to watch.

Items to watch vary depending on the variable type.

8. In the Add Watch Entry dialog box, do one of the following:

– If the watch window you want to use to monitor the variable is open, choose it from the Select Watch Window drop-down list.

– If the watch window you want is not open, click Open. Navigate to it and double-click it to open it.

– If you want to monitor the variable in a new watch window, click New. (For help, see “Creating a Watch Window” on page 165.)

9. When the Add Watch Entry dialog box shows the correct items to watch and the watch window you want, click OK.

The variable appears in the watch window.

Viewing Pointer Variables1. Make sure the strategy is running in Debug mode. On the Strategy Tree, double-click

the pointer variable you want to view.

The View Pointer dialog box appears, showing the pointer’s name, type, and item pointed to.



2. To view the status or value of the item pointed to, click the Inspect button.

If you need help, follow the steps in “Viewing Numeric, String, and Communication Handle Variables” on page 242.

Viewing Numeric and String Tables1. Make sure the strategy is running in Debug mode. On the Strategy Tree, double-click

the table variable you want to view.

The View Table dialog box appears, showing the table’s name, length (maximum number of entries), width for a string table, initialization method, and security level. It also lists the index and value of each table entry. The title bar includes the name of the variable and indicates whether scanning is occurring.

Here’s an example for a string table.

Scanning for an individual table element stops whenever you select an element in the table. It resumes for that element if no changes are made and another table element is selected, or when you click Apply. A magenta background indicates that scanning is stopped.

2. To change the format of the elements, click the button to the right of the Watch button.

VIEWING VARIABLES IN DEBUG MODE


For string tables, you can select either ASCII or Hexadecimal. For numeric tables, you can select Decimal, Hexadecimal, or Binary.

3. To view the configuration information, click More Info.

4. To change a table entry, click its index number, highlight the value, and type in a new value. Click Apply.

5. To monitor the table in a watch window, click Watch.

The Add Watch Entry dialog box appears.

6. In the Add Watch Entry dialog box, do one of the following:

– If the watch window you want to use to monitor the table variable is open, choose it from the Select Watch window drop-down list.

– If the watch window you want is not open, click Open. Navigate to it and double-click it to open it.

– If you want to monitor the variable in a new watch window, click New. (For help, see “Creating a Watch Window” on page 165.)

7. Select the indexes you want to watch.



8. When the Add Watch Entry dialog box shows the correct items to watch and the watch window you want, click OK.

The table variable appears in the watch window.

Viewing Pointer Tables1. Make sure the strategy is running in Debug mode. On the Strategy Tree, double-click

the pointer table you want to view.

The View Table dialog box appears, showing the pointer table’s name, length, and the items pointed to. You cannot change a pointer table entry in this dialog box.

2. To view the status or value of the item pointed to, highlight it in the table and click More Info.

If you need help, follow the steps in “Viewing Numeric and String Tables” on page 245.

Adding CommandsTo make a block in a strategy flowchart do the work it’s intended to do, you add one or more commands. Commands use the I/O points and variables you’ve already configured, as well as other elements in your strategy. A command, for example, might turn on a digital point, move a value to a variable, or check to see whether a chart is running. PAC Control contains more than 500 commands you can use. A command in PAC Control is often called an instruction.

You can add commands to action blocks, condition blocks, and OptoScript blocks. Continue blocks just move flowchart logic to another block. (See “Configuring a Continue Block” on page 253.)

To add commands to an action or condition block, follow the steps below. (To add commands to an OptoScript block, see “OptoScript Functions and Commands” on page 331 and “Using the OptoScript Editor” on page 346.)1. With the strategy open in Configure or Online mode and the flowchart open,

double-click the block to which you want to add a command.

ADDING COMMANDS


The Instructions dialog box appears. The highlighted area shows where the new command will be added.

2. Click Add to open the Add Instruction dialog box.

3. If you know the command you want, enter its name in the Instruction field by typing it in or by choosing it from the drop-down list. Skip to step 7.

4. If you don’t know the command name, click Select to open the following dialog box.

Highlighted area

The Operator group appears in the dialog box only for condition blocks, not for action blocks.



5. Click the name of a command group in the left column to display all the commands in that group. In the right column, click the command you want.

For more information on any command, click the command name and click Command Help to open online help. You can also look up the command in the PAC Control Command Reference.

6. When the command you want is highlighted, click OK to return to the Add Instruction dialog box.

7. (Optional) Enter a comment about the purpose of the instruction.

Comments help explain the command’s purpose in this block and are helpful to anyone who debugs or updates the strategy later.

8. Complete each argument for the command by typing in the Type and Name fields or by choosing from the drop-down lists.

Arguments

ADDING COMMANDS


If the argument type is a literal (or constant), you must type it in. You can use either decimal or hexadecimal form.

If you type in the name of an item that doesn’t exist, for example a variable or I/O point, you are prompted to add it to the strategy.

Each command requires a certain number of arguments, from zero to eight. For help in completing arguments, see the PAC Control Command Reference or the online help for the specific command you’re using.

9. When the arguments are complete, click OK.

You return to the Instructions dialog box, which now shows the command you just added. Notice that the comment you entered appears just above the command. The arguments you entered appear as part of the instruction. The highlight shows where the next command will be placed if you add another command to this block.

Here is an example of an Instructions dialog box for an action block:

10. To add another command, click to place the highlight where you want the command to appear. Click Add and repeat the steps in this section.

If you highlight a command that’s already in the dialog box, the new command will appear just before it.

TIP: If you are adding commands to several blocks at once, you can quickly move from block to block in the chart by clicking the Next Block or Previous Block buttons in the Instructions dialog box.

If you’re working with a condition block, clicking Next Block opens a dialog box so you can select which block to choose, since condition blocks have two exits. The same dialog box appears if you click Previous Block and the block you’re working with has connections coming from more than one block.

11. If you put more than one command in a condition block, complete the Operator group as follows:

– If both commands must be true to exit the block true, click AND.

Comment

Arguments

Highlight

Command



– If only one of the commands must be true to exit the block true, click OR.

Here is an example of an Instructions dialog box for a condition block with two commands. In this case, the block will exit true if either of the commands is true.

Changing a Command1. With the strategy open in Configure or Online mode and the flowchart open,

double-click the block containing the command you want to change.

NOTE: To change commands in OptoScript blocks, see “Using the OptoScript Editor” on page 346.

2. In the Instructions dialog box, double-click any line of the command you want to change.

You can also click the command to highlight it and click Modify.

3. In the Edit Instruction dialog box, make the necessary changes.

For help, see “Adding Commands” on page 247.

4. Click OK to return to the Instructions dialog box, where you can see the changed command.

Deleting a CommandYou can delete a command permanently, or you can comment out a command so it is temporarily skipped, usually for debugging purposes.

Permanently Deleting a Command 1. With the strategy in Configure or Online mode and the flowchart open, double-click

the block containing the command you want to delete.

Either the first command OR the second command can be true for this condition block to exit true.

CUTTING OR COPYING A COMMAND


NOTE: To delete commands in OptoScript blocks, see “Using the OptoScript Editor” on page 346.

2. In the Instructions dialog box, click any line of the command you want to delete.

CAUTION: Make sure you select the correct command. You cannot undo a deletion!

3. Click Delete or press DELETE on the keyboard.

Commenting Out a CommandYou can mark certain commands so that the strategy temporarily ignores them. Commenting out one or more commands can help you pinpoint problems in a strategy.1. With the strategy in Configure or Online mode and the flowchart open, double-click

the block containing the command(s) you want to comment out.

NOTE: To comment out commands in OptoScript blocks, see “Using the OptoScript Editor” on page 346.

2. In the Instructions dialog box, click the first command you want to comment out. Click Add.

3. In the Add Instructions dialog box, choose the instruction Comment (Block). Click OK.

You return to the Instructions dialog box, and all the instructions in the block from that point on are grayed out, indicating that they will be ignored when the strategy runs.

4. Click just beyond the last command you want to comment out. Add another Comment (Block) instruction.

When you return to the Instructions dialog box, all commands between the two Comment (Block) instructions are grayed out.

5. When you no longer want the strategy to ignore the command(s), delete the two Comment (Block) instructions.

NOTE: The Comment (Block) command is used for this purpose. The Comment (Instruction) command just places an explanatory comment in the Instructions dialog box. It does not affect any commands.

Cutting or Copying a CommandFor commands in action, condition, and continue blocks you can cut or copy commands to the Windows clipboard and then paste them in the same block or in another block, or even in a block of another chart within the same strategy. For OptoScript blocks, see “Using the OptoScript Editor” on page 346.1. With the strategy in Configure or Online mode and the flowchart open, double-click

the block containing the command you want to cut or copy.2. In the Instructions dialog box, click any line of the command you want to cut or copy.



To cut or copy more than one command, hold down the SHIFT key while you click all the commands to be cut or copied at once.

NOTE: To cut and paste all commands in a block, copy and paste the entire block, and then change its name if necessary.

3. Press CTRL+X to cut the command(s) or CTRL+C to copy them.

You can also click the right mouse button and choose Cut or Copy from the pop-up menu.

The command is cut or copied to the Windows clipboard.

Pasting a CommandOnce you have cut or copied a command, you can paste it into any block in the same strategy.

Choose one of the following, and then press CTRL+V:

• To paste the command in the same block, click where you want to insert the command.

• To paste the command at the end of the instruction block, move the cursor just below the last instruction and click to highlight the empty space.

• To paste the command to another block, click Close to exit the current Instructions dialog box and double-click the block where you want to place the command. Click where you want to insert the command.

Configuring a Continue BlockContinue blocks do only one thing: jump to another block. Thus, the only information you need to provide in a continue block is the name of the block to jump to.1. With the strategy in Configure or Online mode and the flowchart open, double-click

the continue block you want to configure.

You can also click the block, click the right mouse button, and choose Detail from the pop-up menu.

The Select Continue Block Destination dialog box appears, listing all blocks in the chart.

VIEWING AND PRINTING CHART INSTRUCTIONS


2. Click the destination block and click OK.

Viewing and Printing Chart InstructionsTo view or print commands in a chart, see “Viewing and Printing Strategy or Subroutine Commands” on page 197.


10: 10: Programming with CommandsChapter 10

10: Programming with Commands

IntroductionCommands (or instructions) in PAC Control are roughly grouped by function. This chapter tells you what you need to know about each group in order to program your PAC Control strategy effectively. For detailed information on using a command, see the PAC Control Command Reference.

In this ChapterAnalog Point Commands...................................... 256Chart Commands ..................................................... 258Communication Commands............................... 259Control Engine Commands.................................. 282Digital Point Commands ....................................... 283Error Handling Commands................................... 288I/O Unit Commands ................................................ 289I/O Unit—Event Message Commands ........... 291I/O Unit—Memory Map Commands .............. 292I/O Unit—Scratch Pad Commands .................. 293Logical Commands.................................................. 295Mathematical Commands.................................... 297Miscellaneous Commands ................................... 301PID—Ethernet Commands.................................. 302Pointer Commands.................................................. 306Simulation Commands .......................................... 308String Commands .................................................... 309Time/Date Commands........................................... 318Timing Commands .................................................. 319

ANALOG POINT COMMANDS


Analog Point CommandsThe following commands are used with analog points:

Offset and Gain CommandsThe easiest way to set offset and gain is to do so when you configure analog points in PAC Manager, using the Calibrate button in the Configure I/O Points dialog box. analog point

You can also set offset and gain in PAC Control. If you already know the offset and gain for a point, you can use the commands Set Analog Offset and Set Analog Gain. If you do not know the offset and gain, you can use the commands Calculate & Set Analog Offset and Calculate & Set Analog Gain to have the brain calculate them. Calculate offset first, and then calculate gain.

By setting offset and gain, you make sure that values read are accurate.

Offset is the difference between the minimum input of an analog input point and the actual minimum signal received from a field device. For example, if a 4–20 mA input receives a minimum signal that is slightly off (not exactly 4 mA), the difference between the two minimums is the offset. Reading ± Offset = Actual Value. For example:

Gain is the difference in the full-scale reading, but expressed differently.Measured Value ∗ Gain = Actual Value. For example:

Offset and Gain Others

Calculate & Set Analog Gain Set Analog Filter Weight

Calculate & Set Analog Offset Set Analog Load Cell Fast Settle Level

Set Analog Gain Set Analog Load Cell Filter Weight

Set Analog Offset Set Analog TPO Period

Minimum/Maximum Values

Get Analog Maximum Value

Get Analog Minimum Value

Get & Clear Analog Maximum Value

Get & Clear Analog Minimum Value

If minimum input = 4.000 mA

and zero-scale reading = 4.003 mA

then offset = -0.003 mA

If maximum input = 20.00 mA

and measured value = 20.50 mA

then gain = 0.9756097560976

CHAPTER 10: PROGRAMMING WITH COMMANDS


Minimum/Maximum ValuesThe Opto 22 brain automatically keeps track of minimum and maximum values for analog input points. Min/max values are often used to monitor pressure or temperature.

To read the minimum or maximum value and leave it as is, use Get Analog Minimum Value or Get Analog Maximum Value. To read the minimum or maximum value and clear it—for example, to record the minimum pressure in each 24-hour period—use Get & Clear Analog Minimum Value or Get & Clear Analog Maximum Value.

Analog Points and OptoScript CodeIn OptoScript code, an analog I/O point can be used directly, wherever a float variable can be used. For example, you can assign an analog point a value, or use points directly in mathematical expressions and control structures. For more information, see “Using I/O in OptoScript” on page 331.

CHART COMMANDS


Chart CommandsThe following commands control charts in the strategy:

For information about charts in a PAC Control strategy, see “PAC Control Terminology” on page 51.

About the Task QueueHow do subroutines fit into the task queue?

Whenever a chart calls a subroutine, the subroutine temporarily inherits the task in use by the calling chart along with its priority.

Does a task always use all of its allocated time?

Not always. If a chart or subroutine runs in a loop, all allocated time is used. If a chart or subroutine does not need all of its allocated time to complete its job, all remaining time (including any portion of a time slice) is given up.

The following conditions cause a chart to use less than a full time slice:

• The chart or subroutine stops.

• The chart or subroutine is suspended.

• A Delay command is used.

Using the command Delay (mSec) with a value of 1 millisecond is a handy way to give up the time slice while waiting in a loop for a condition to become True. For more information, see form 1776, Optimizing PAC Project System Performance.

When does the requested change to a chart or task status take effect?

Not immediately. In any multitasking system, timing and synchronization issues are always a concern. The time required for a particular request to be implemented depends on the number of tasks currently running and the specified chart’s location in the task queue. We recommend using commands such as Calling Chart Suspended? and Chart Running? to determine the status of a chart.

Call Chart Continue Calling Chart

Calling Chart Running? Continue Chart

Calling Chart Stopped? Get Chart Status

Calling Chart Suspended? Start Chart

Chart Running? Stop Chart

Chart Stopped? Suspend Chart

Chart Suspended?



Communication CommandsThe following commands refer to moving data among entities that store and transfer data:

Communication HandlesA communication handle is a variable in PAC Control that stores the parameters needed to connect to a specific entity; the entity may be another device on the network, a file located on the control engine, or some other thing that stores or transfers data. The value of the communication handle variable is a string consisting of the communication parameters separated by colons.

Typically, a communication handle is used to open communication, to transmit and receive data, and to close communication. For example, you might use the TCP communication handle to communicate with another device on the network via TCP/IP, or the FTP communication handle to send data from the brain to a file on a PC.

In many cases you’ll define a communication handle variable and never change it, because the same parameters are always needed. However, in some cases it might be useful to change it. For example, if you use the same process to send serial data through two different serial communication modules, you can use Set Communication Handle Value to switch to the other module. Advanced users may also want to use pointers.

Set Communication Handle Value also allows you to retrieve the communication timeout value for some types of communication handles, and you can specify the communication timeout value in seconds.

Several types of communication handles are available:

Accept Incoming Communication Receive String

Clear Communication Receive Buffer Receive String Table

Close Communication Send Communication Handle Command

Communication Open? Set Communication Handle Value

Get Available File Space Set End-Of-Message Terminator

Get Communication Handle Value Transfer N Characters

Get End-Of-Message Terminator Transmit Character

Get Number of Characters Waiting Transmit NewLine

Listen for Incoming Communication Transmit Numeric Table

Open Outgoing Communication Transmit Pointer Table

Receive Character Transmit String

Receive N Characters Transmit String Table

Receive Numeric Table Transmit/Receive String

Receive Pointer Table

* PAC Control Professional only; mistic I/O units only

TCP For Ethernet communication For communication with serial modules

See page 261.See page 265.

COMMUNICATION COMMANDS


Adding Communication Handles

Using the Add Variable dialog box, you can create a communication handle for each of the four types (TCP, File, FTP, and Serial) mentioned in the previous section. For more information on adding variables, see “Adding Variables” on page 233.

To add a communication handle:1. In the Strategy Tree, under Variables, right-click Communication Handles, then choose

Add to open the Add Variable dialog box.

2. At minimum, enter the following things:

– Name: Create an appropriate name, such as TCP_Handle.

– Type: Select Communication Handle.

– Initial Value: Varies with type. For TCP, see page 261. For File, see page 269. For FTP, see page 275. For Serial, see page 278.

File For creating a file to be stored on the control engine, and reading or writing to a file stored on the control engine

See page 269.

FTP For accessing files on the local file system or another FTP server, including transferring files between the two servers

See page 275.

Serial For using the RS-232 connectors on a SNAP PAC controller to communicate with serial devices. (Not used for serial communication modules or serial-based I/O units.)

See page 278.

Name

Type

Initial Value



Using TCP Communication HandlesThe TCP communication handle is used for most Ethernet communication. Any device on the network accessible via TCP/IP can be communicated with using communication commands. For example, data from a serial device can be received through a serial communication module, or communication can be established with a PC on the network.

NOTE: If the two devices that are sharing data are both control engines, it may be easier to use the Scratch Pad areas on each to transfer data, rather than using communication commands. See “I/O Unit—Scratch Pad Commands” on page 293 for more information.

NOTE: Be sure to use a separate TCP communication handle for each chart in a strategy. If two charts were to run simultaneously while sharing an open communication handle, each chart would be able to read and write data from the communication handle as if the other running chart didn't exist. Because these reads and writes are not synchronized between the charts, it is possible for one chart to read the other chart's data.

Incoming and Outgoing Communication

TCP communication is normally requested by the device that needs the data. For example, a PAC Control strategy running on SNAP PAC I/O unit A might need the value of a set of variables from another strategy running on SNAP PAC I/O unit B. Unit A would request communication using the command Open Outgoing Communication. Unit B would Listen for Incoming Communication and then Accept Incoming Communication to establish the connection. Once connected, data could be transmitted and received in both directions.

This scenario is similar to the way we use the telephone. If Joe Wong needs information from Saul Garcia, he requests communication by calling Saul on the phone (opening outgoing communication). If Saul is there (listening for incoming communication), he answers the phone (accepts incoming communication), and the connection is completed. Once connected, both Joe and Saul can talk and listen to transmit and receive information.

Depending on the situation, you may want to have both peers request communication and establish two connections between them. That way if one peer goes offline and then comes online, you can have the flowchart logic set up to immediately open communication again.

In some cases, however, one of the devices may be incapable of requesting communication. A serial device such as a barcode reader attached to a serial communication module on a SNAP PAC I/O unit is an example. The serial device is incapable of requesting Ethernet communication; essentially it acts as a slave device and can only wait until it is asked for data. For serial devices attached to serial communication modules, the control engine needing the serial data must request communication using Open Outgoing Communication. (For serial devices attached directly to a serial port on a SNAP PAC controller or brain, see “Using Serial Communication Handles to Communicate with Serial Devices” on page 278.)

Outgoing Communication. For outgoing communication (communication you request), the communication handle’s value is in the format tcp:<IP address>:<port>. Note that



tcp is all lowercase letters. The following table shows examples of communication handles for outgoing communication.

To add a communication handle, see the steps starting on page 260. In the Add Variable dialog box, enter the communication handle value in the Initial Value field.

Port Numbers. If you are talking to other control engines or other peers on the network, you can use any port number that is not already in use by that device. For example, you can safely use ports 22004 and 22005, which have been assigned to Opto 22 by the Internet Assigned Numbers Authority (IANA). Opto 22 has allocated these Ethernet TCP port numbers for customer use. In general, anything below 1024 is already predefined and shouldn't be used unless you are implementing one of the predefined protocols that already has a reserved port. The following port numbers are reserved by Opto 22 devices for the purposes shown.

Outgoing CommunicationCommunication Handle Value

Protocol:IP Address:Port

Ethernet TCP - to another control engine tcp:10.192.56.185:22004

Ethernet TCP - to a serial communication module on another rack tcp:10.192.54.10:22506

Ethernet TCP - to a serial communication module on the same rack (uses SNAP PAC R-series IP address or loopback IP address)

tcp:10.192.55.90:22511 ortcp:127.0.0.1:22511

Port # Purpose

20 FTP (file transfer protocol) for get, send, and dir functions

21 FTP (file transfer protocol)

25 SMTP (simple mail transfer protocol)

161 SNMP-based enterprise management systems

502 Modbus/TCP

Communication handle value



Note that port numbers on the SNAP PAC controllers and brains are the default ports; some may have been changed for security reasons. (See the section on Security in form 1704, the PAC Manager User’s Guide.)

If you do not know what port number to use, ask your network administrator or check the list of standard reserved Ethernet port numbers at www.iana.org/assignments/port-numbers to see ports that may apply to your devices on your network.

Incoming Communication. For incoming communication (communication requested by another device), the communication handle value includes just the protocol and the port number: Protocol:Port. TCP automatically tracks senders so there is no mix-up in the data sent and received. Here are a couple of examples of communication handles for incoming communication:


2001 Main command processor, OptoMMP-based (also used by SNAP PAC controllers and brains)

2222,44818 Ethernet/IP

22000 Opto 22 controllers and brains

22001Host port (for information on configuring the host port, see form 1704, the PAC Manager User’s Guide)



22500–22531 Serial communication modules

50000–50999 Internal messaging

Incoming CommunicationCommunication Handle Value

Protocol:Port

Ethernet TCP - from another control engine tcp:22004

Ethernet TCP - from another control engine tcp:22005

Port # Purpose



Opening and Closing TCP/IP Communication Handles

When using TCP/IP communication handles (a communication handle’s value that begins with “tcp:”), keep in mind that the controller has a limited amount of TCP/IP resources, and so you need to be careful about how frequently these communication handles are opened and closed. TCP/IP handles are meant to be left open as long as possible.

Per the TCP/IP specification, each time one of these resources are closed, they are unavailable for 120 seconds. Rapidly attempting to open and close TCP/IP communication handles quickly places all available resources in the unavailable condition.

Once this unavailable state occurs, a communication handle will be unable to gain a resource upon the next Open Outgoing Communication command. This effectively causes a lock out of any new TCP/IP connections to be made with the controller (whether from the strategy or externally).

The lock out affects applications such as PAC Control, PAC Display, PAC Manager, OptoOPCServer, and PAC Terminal. These applications will either have intermittent or no connectivity with the controller.

The solution to this dilemma is to control the rate at which TCP/IP communication handles are opened and closed. When a TCP/IP communication handle is closed (whether a result of a prior successful or unsuccessful opening), it should be reopened no sooner than 3 seconds. If this reopening fails to succeed, double the delay to 6 seconds. If this subsequent reopening fails, double the delay to 12 seconds. And thereafter, subsequent reconnections should be performed no shorter than every 24 seconds. This throttling of the opening allows several TCP/IP resources to expire their closing timer.




TCP Communication Handle Examples

The following diagram shows an example of a communication handle value for outgoing communication:

For incoming communication, the communication handle value could be:

Communication Handles for Serial Communication Modules. For communication with serial devices through a serial communication module, the communication handle value consists of the IP address of the brain the module is attached to, plus the serial module’s port number according to its position on the rack. For port number information, see Opto 22 form 1191, the SNAP Serial Communication Module User’s Guide.

Here are two examples of communication handles for communicating with serial modules, the first showing communication through a module on the same rack as a SNAP PAC

SNAP R-series I/OIP address: 10.192.59.45

Device AIP address: 10.192.59.31

Receives communication on port 22004

Communication Handle value:tcp:10.192.59.31:22004

Outgoing Communication

Request communication

Communicate


Device AIP address: 10.192.59.31

Sends communication to 10.192.59.45 on port 22004

Communication Handle value:tcp:22004

Incoming Communication

Communicate

Request communication



R-series controller, and the second showing communication through a module on a different rack.

Using Flowcharts to Control TCP/IP Communication

When a control engine is communicating with another device using TCP/IP, it runs a PAC Control flowchart or charts to control communication.

• For outgoing communication on controller COM ports and serial modules, the flowchart uses the command Open Outgoing Communication to request a connection.

• For incoming communication on controller COM ports, which is requested by another device, the flowchart must first use Listen for Incoming Communication and then use Accept Incoming Communication to establish a connection.

• For incoming communication on serial modules, which is requested by another device, the flowchart uses the Open Outgoing Communication and Communication Open? commands to establish a connection.

The control engine’s TCP/IP flowcharts should open communication once and then continue to transmit or receive using the communication handle. Constantly opening and closing communication for each transaction wastes time and is inefficient.

SNAP R-series I/OIP address: 10.192.59.45 Serial Device

Communication Handle value:tcp:127.0.0.1:22507or tcp:10.192.59.45:22507

To a Serial Module on the Same Rack

SNAP-SCM port 22507

For a serial module on the same rack, use the loopback IP address 127.0.0.1, which tells the brain to talk to its own rack. You can also use the brain’s own IP address (in this example, 10.192.59.45), but the loopback address allows you to change the IP address of the brain without having to change the communication handle.


Communication Handle value:tcp:10.192.59.62:22507

To a Serial Module on a Different Rack

Serial DeviceEthernet network

SNAP-SCM port 22507

SNAP EB-series I/OIP address: 10.192.59.62



As a simple example, the flowchart at right is designed to receive data from a serial device, such as a barcode reader, through a serial communication module on the same rack as a SNAP PAC R-series I/O unit.

Communication with serial modules is done via TCP/IP. It can be done from the SNAP PAC R system itself, as in this example, or from another TCP/IP device on the network.

In this example, the R-series I/O unit establishes communication through the serial module using the communication handle: tcp:127.0.0.1:22507

The loopback IP address is used, since the serial module is on the same rack.

When characters are detected in the receive buffer, the I/O unit receives the string and processes it, and then after a short delay checks for another message. Communication remains open for additional messages.

This simple flowchart illustrates the basics of handling communication, without any error checking. However, while receiving and transmitting, TCP/IP control charts should also monitor the status value returned by commands such as Transmit Numeric Table and Receive Numeric Table, and close communication if there are errors. If your PAC Control application opens sessions but does not close unused or bad sessions, the maximum number of sessions could be used up. Note that communication should not be closed for timeout errors from Receive commands (error numbers –37 and –39), however, because these errors simply mean that there was no data waiting in the receive buffer for the specified session.

To save time, before using a Receive command (such as Receive String or Receive Numeric Table), TCP/IP charts should use the command Get Number of Characters Waiting. If there are zero characters waiting, then there is no reason to use the Receive command. It is also a good idea to start a down timer, and then loop on the Get Number of Characters Waiting command until either there are more than zero characters waiting, or the timer expires.

The following chart is also an example of TCP/IP communication on controller COM ports, but with three differences: in this case another device is requesting communication, the peer will both transmit and receive, and error checking is shown for the commands Get Number of Characters Waiting and Receive Numeric Table. Similar error checking should be used for transmit commands, which in this strategy are in another chart.



If the devices communicating with each other are all SNAP R-series, be careful not to have one of them send information to another faster than the receiving system can pull it out of its receive buffer. When a control engine receives data from the Ethernet network, it holds the data in memory (the buffer) until the PAC Control flowchart removes it with a Receive command. If the data is not removed fast enough, the receive buffer will fill up. You can prevent this problem by transmitting the information less frequently. If the same chart is transmitting and receiving, you can alter the chart so that it receives more often than it transmits.

Ethernet Connections and Ports

The number of Ethernet connections available varies by hardware, type, and in some cases firmware version, such as 80 on current SNAP R-series I/O systems.

The host connection is on port 22000 or 22001 and is used to communicate with the PC that runs PAC Control. These port numbers are reserved for this purpose, but they can be configured. For information see Opto 22 form 1704, the PAC Manager User’s Guide.

Peer-to-peer connections can be on any other port number that is not already used on the network; these connections are used to communicate with other control engines or other devices on the network. When you assign port numbers for peer-to-peer connections, make sure you do not assign port numbers that devices on your network may use for specific purposes. For a list of standard Ethernet port numbers, refer to: www.iana.org/assignments/port-numbers



IMPORTANT: If you are using TCP/IP connections, consult commercially available texts on TCP/IP that discuss client/server architectures, so you’ll understand how the protocol works and what to expect during communication.

Using the Control Engine’s File SystemThe memory in SNAP PAC controllers includes a substantial area (about 4 MB on a SNAP-PAC-S1, or 2 MB on a SNAP PAC R-series controller) available for file storage. Any types of files can be stored there, and files can be sorted into directories or folders just as they can on a PC. These stored files are then available for use; for example, the control engine can read them, add data to them, and even send data from them via FTP to another device on the network. SNAP PAC controllers also allow you to store data or files using a microSD card. For more information about using a microSD card, see the user’s guide for the controller.

NOTE: Certain FTP commands may also be useful when dealing with files, even if the files are all local. For example, the dir command is available with comm handles.

The file communication handle is used to create, write to, and read from stored files on the control engine. The format for the handle’s value is: file:<open mode>,<filename>

Note that file is all lowercase. Open modes are:

Here are some examples of file communication handle values:


Open mode Description

r Opens a file for reading. If the file does not exist or cannot be found, the open call fails.

w Creates a new file and opens it for writing. If the file already exists, its contents are destroyed.

a Opens a file for writing at the end of the file (appending). If the file doesn’t exist, it is created.

Creates the file myfile.txt and opens it for writ-ing. file:w,myfile.txt

Opens the existing file myfile.txt so data can be appended to it. file:a,myfile.txt

Creates the file Temperature data. txt in the directory Data_files and opens it for writing. If the directory doesn’t exist, it is created.

file:w,/Data_files/Temperature data.txt

Opens the file Temperature data.txt in the directory Data_files for reading. file:r,/Data_files/Temperature data.txt



Keep the following limitations in mind as you use the file communication handle with the controller’s file system (see below for microSD card):

If power to the control engine is turned off, files are destroyed unless they have been saved to flash memory. See “Commands Relating to Permanent Storage” on page 282 for information on saving files to flash using PAC Control commands.

Using a File on a microSD Card

If your SNAP PAC controller has a microSD card slot in the top of the controller’s case, you can use PAC Control commands with files on a microSD card just as you would with any other file in the controller’s file system. Just remember two things:

• Include the card’s directory name in the path in the file communication handle, for example: file:a,/sdcard0/VoltLog.txt

• Since long filenames are not supported, all files you store on the card must be named with a maximum of eight characters in the name plus three characters in the extension (8 dot 3 format), for example: datafile.txt

Maximum length for filenames and directory names 127 characters

Filename characters allowed All ASCII characters except *, ?, null, and /

Path name component separator /

Maximum number of files and directories that can be open simultaneously 16

Maximum directory depth Limited only by available memory

Maximum number of filesLimited only by available memory. Each file uses 516 bytes of overhead plus its number of bytes rounded up to the nearest multiple of 516 bytes.

Maximum number of directories Limited only by available memory. Each directory uses 516 bytes.

Maximum amount of memory available in the control engine’s file system

Approximately 4 MB on a SNAP-PAC-S1, or 2 MB on a SNAP PAC R-series controller (varies slightly depending on the control engine firmware version)




Using the microSD card with FTP, you can read the card at 380 kB/s and write to it at 231 kB/s.

For more information on using the microSD card, see the controller’s user guide.

Working with Files in Your Strategy

The commands you use with a communication handle vary according to the action (the open mode) defined in the handle’s value. To change actions—from read to write, for example—you can use Set Communication Handle Value to change the handle’s value.

To work with files in your strategy, first use the command Open Outgoing Communication.

Writing to a File. For example, suppose you have data in your strategy in a string table (Product_Table) that you want to write to a file (Products.txt) in a directory (Company Data) on the control engine. Here’s how you would do it:1. Use Open Outgoing Communication to open a file communication handle. The value

of the handle would be: file:w,/Company Data/Products.txt2. Use the condition Communication Open? to make sure the communication handle

opened.3. To put the data from the string table into a comma-delimited file (which is easy to

open in database software), use the command Set End-Of-Message Terminator to indicate that a comma should be used as the delimiting character.

Commands to use with any file communication handle

Commands to use with file comm handles in Read mode

Commands to use with file comm handles in Write or Append mode

Close CommunicationCommunication Open?Get Available File SpaceGet Number of Characters WaitingOpen Outgoing CommunicationSend Communication Handle Command (delete, getpos, or setpos)Set Communication Handle ValueSet End-of-Message Terminator

Receive Numeric TableReceive Pointer TableReceive StringReceive String TableSend Communication Handle Command (find)

Transfer N CharactersTransmit CharacterTransmit NewLineTransmit Numeric TableTransmit Pointer TableTransmit StringTransmit String Table



4. Use the command Transmit String Table to transmit data from Product_Table directly into the Products.txt file. Items from the string table are separated by commas in the file.

5. Use the command Close Communication to close the communication handle.

Reading a File. As another example, suppose you have a file on the control engine that was placed there via FTP. (See the next section for details on using the FTP communication handle.) You want to read this file (New_Data.txt) and place the data in it into a string table (Data_Table) in your strategy.1. Use Open Outgoing Communication to open a file communication handle. The value

of the handle would be: file:r,New_Data.txt2. Use the condition Communication Open? to make sure the handle opened. 3. Use the command Set End-Of-Message Terminator to indicate what character in the

New_Data.txt file should be read as the delimiting character. (In the example shown below, it’s a slash.)

4. Use the command Receive String Table to receive the data from New_Data.txt directly into Data_Table.

Notice the numbers used in this example. These are numbers represented as strings. For the purpose of storing and sending data, this is the simplest way to represent them. If you need to use them in calculations, however, you must first convert them to numeric values. You can do so in your PAC Control strategy by using a command such

Product_Table

0 Bats

1 Baseballs

2 Batting gloves

3 Catcher’s mitts

StrategyControl Engine File System

Company Data/ Products.txt

Bats,Baseballs, Batting gloves, Catcher’s mitts

Data_Table

0 485

1 622

2 35

3 56

4 7841

5 20

StrategyControl Engine File System

New_Data.txt

485/622/35/56/ 7841/20



as Convert String to Float or Convert String to Integer 32. (See “String Commands” on page 309 for more information.)

5. Finally, close the communication handle by using the command Close Communication.

A More Complex Example . Here’s a more complex example which shows the actual OptoScript code. In this example, someone on the network needs the value of several variables in the PAC Control strategy running on the control engine. This person has sent to the control engine via FTP a comma-delimited text file (ProductRequest.txt) containing the names of the variables. (See page 275 for information on FTP.)

This section of the PAC Control strategy reads the variable names from the text file in the control engine’s file system and places the names in a string table (Product_Names). Next, the strategy uses the command Get Value From Name to place the values of the variables into another table (Product_Info). The data from this table is then written to another text file (ProductInfo.txt) on the control engine, which can later be sent via FTP to the person who requested the data.

The whole operation (including the FTP portions, which are not covered in this code example), might look like this:

Requestor Control Engine File System

PAC Control Strategy

ProductRequest.txt

ProductSales.txt

Num_Widgets, Num_Gadgets, Num_Thingies, Num_Whatnots

9556, 10867, 5432, 23

ProductRequest.txt

Num_Widgets, Num_Gadgets, Num_Thingies, Num_Whatnots

ProductInfo.txt

1

Product_Info String Table

0 9556

1 10867

2 5432

3 23

Product_Names String Table

0 Num_Widgets

1 Num_Gadgets

2 Num_Thingies

3 Num_Whatnots

2

3

45

FTP

FTP

Get Value From Name

9556, 10867, 5432, 23



The OptoScript code in this example also makes use of the command Set Communication Handle Value to change the value of a specific communication handle during the operation.

Deleting Files and Moving Within Them. Another command you’ll find useful with file communication handles is Send Communication Handle Command. Using these commands, you can delete files, find a position within the file, and jump to a specific position within the file. See the PAC Control Command Reference or online Help for details.

Sets the value for the communication handle chAFile.

SetCommunicationHandleValue("file:r,ProductRequest.txt",chAFile);

Opens the communication handle and checks to make sure it opened.

status = OpenOutgoingCommunication(chAFile);if (status == 0) then

Sets the end-of-message terminator to a comma because the file to be read is comma-delimited.

SetEndOfMessageTerminator(chAFile, ',');

Reads the contents of the file Product_Names into a string table.

status = ReceiveStrTable(4,0,Product_Names,chAFile);

Loops through the items in Product_Names table and places the values they represent into another string table, Product_Info. (Note that the “numbers” in the Product_Info table are not true numbers, but string representations of numbers.)

index = 0;while ((index < 4) and (status == 0))

status = GetValueFromName(Product_Names[index], Product_Info[index]); index = index + 1;wend

Closes communication. status = CloseCommunication(chAFile);

Changes the value of the communication handle; it is now set to write to the file ProductInfo.txt on the control engine.

SetCommunicationHandleValue("file:w,ProductInfo.txt",chAFile);


status = OpenOutgoingCommunication(chAFile);if (status == 0) then

Makes the ProductInfo.txt file comma-delimited, too.

SetEndOfMessageTerminator(chAFile, ',');

Writes the data from the Product_Info string table into the ProductInfo.txt file on the control engine.

status = TransmitStrTable(4,0,Product_Info,chAFile);endifendif



Moving Files via FTPAs explained in the previous section (“Using the Control Engine’s File System,” starting on page 269) the control engine’s memory includes a substantial area available for file storage. You can move files to and from file storage using the File Transfer Protocol (FTP):

• To move files to and from file storage using another device such as a PC, use any standard FTP software. See instructions in Opto 22 form 1704, the PAC Manager User’s Guide. A maximum of five devices can FTP files to a control engine simultaneously.

• To move data to and from file storage programmatically, a strategy can request or send a file using an FTP communication handle, explained in this section. A maximum of 16 communication handles can be used simultaneously to move data via FTP.

FTP also allows you to get a directory listing of files on a remote server or in the local file storage area. In addition, if your SNAP PAC controller has a microSD card slot in the top of the controller’s case, you can use the FTP communication handle to manipulate files on a microSD card.

FTP Communication Handle Examples

The value for the FTP communication handle is in the format:ftp:<IP address>:<port>,<username>,<password>,<optional timeout>

Here are two examples of FTP communication handle values:

ftp:10.22.55.35:21,jsmith,2towers,60 (timeout increased to 60 seconds)

ftp:10.192.54.195:21,m,m (no timeout specified)


ftp Use all lowercase letters.

IP address IP address of the destination device (where the file will go).

port Default port is 21, with 20 for the data port.

usernamepassword

Enter the username and password set up for the destination device. If the destination device is another control engine or the local server, use anything except an empty string.

optional timeoutSpecify a communication timeout value in seconds, or leave this parameter out to use the default of 30 seconds.



Using FTP Communication Handles in Your Strategy

Suppose you have data you need to send via FTP to a device on the network whose IP address is 10.192.56.45. Your username on this device is JoeG and your password is hello. You expect the default timeout of 30 seconds to be adequate.

There are two ways you can send the data: all at once, or in pieces over time. If your data file is less than 1 MB in size, you can send it all at once. If it is larger, or if you want to append additional data to a file that already exists, you send it in pieces.

Sending the Data All At Once. This method is better for small data files; files larger than 1MB may take a long time to transfer, and the control engine may become unresponsive during the process.

Suppose you want to place the data into a file (HunkoData.txt) on the device; the data is currently in the file UseThisData.txt on the control engine. Here’s how you would send the data in your PAC Control strategy:1. Use the command Open Outgoing Communication to open an FTP communication

handle. The value of the handle would be: ftp:10.192.56.45:21,JoeG,hello2. Use the condition Communication Open? to make sure the communication handle

opened.3. Use the command Send Communication Handle Command to specify the filename

and send the file in one step. The communication handle you send is:send:UseThisData.txt,HunkoData.txt

If the remote filename already exists, it is overwritten.

4. When you have finished sending data from the file, use the command Close Communication to close the communication handle.

Sending the Data in Pieces. To append data to an existing file, or to send a very large file (larger than 1 MB), you can send data in pieces.

Suppose you want to append data from a strategy variable or table to an existing file named HunkoData.txt on the device. Here’s how you would send the data:




1. Use the command Open Outgoing Communication to open an FTP communication handle. The value of the handle would be: ftp:10.192.56.45:21,JoeG,hello

2. Use the condition Communication Open? to make sure the communication handle opened.

3. To specify the filename on the remote server, use the command Send Communication Handle Command. The communication handle command you send is:dest:HunkoData.txt

4. Use a Transmit command (such as Transmit String or Transmit Numeric Table) to send the data. In the command, use the name of the FTP communication handle you just opened.

The data is appended to the file. (If the remote filename is new, the file is created and the data placed in it.)

5. When you have finished sending data, use the command Close Communication to close the communication handle.

If you are sending a large file from the control engine to the device, you would need to open up two communication handles: an FTP handle just like the one in the example above, and a File handle for the file on the control engine. Then use the Transfer N Characters command to send the file in chunks.

For another example, see the diagram in “A More Complex Example” on page 273, which shows how FTP communication handles and file communication handles might be used together. See the PAC Control Command Reference or online Help for detailed information on commands.

Retrieving a Directory Listing

The OptoScript code in this example makes use of the command Set Communication Handle Value and the dir option to retrieve a directory listing.

Sets the value for the communication handle chAFile.

// Configure the chFTP comm handle to log into itself. The username and// password don't matter--they just can't be left empty. We'll use the// loopback address of 127.0.0.1 so this code is more portable.SetCommunicationHandleValue("ftp:127.0.0.1:21,noimporta,whocares", chFTP);


// Open the communication handle (log in to the local server)nStatus = OpenOutgoingCommunication( chFTP );if (nStatus == 0) then

Requests directory listing, returns number of listings.

nStatus = SendCommunicationHandleCommand( chFTP, "dir" );

Makes sure “dir” worked—firmware must be version 7.1 or greater.

if (nStatus >= 0) thennFileCount = nStatus;



Using Serial Communication Handles to Communicate with Serial DevicesSerial connectors are located on the top of SNAP PAC controllers. These ports can be used for maintenance, such as loading new firmware, or for Point-to-Point Protocol (PPP) communication via a modem. They can also be used to send or receive data directly from a serial device, such as barcode readers, weigh scales, I/O, or any intelligent device. Serial communication handles are used to communicate with these intelligent devices (see examples below).

First, the serial port must be set to None in PAC Manager, as follows:1. Open the Inspect window in PAC Manager and enter the IP address for your device.2. Click Communications and choose Communication Port Control.3. In the Value field for the Control Function of the serial port you want to use, select

None from the drop-down menu.

NOTE: For a SNAP-PAC-S2, you can configure any of the serial ports as a either RS-232 or RS-485 by changing the Value field for the Mode for Communication parameter.

For more detailed information on setting serial communications, see the PAC Manager User’s Guide.

Reads in listings to stList.

NOTE: Each listing from an Opto 22 device server ends with these hex bytes: 0D 0A and is delineated from the next by a 00.

// Set the EOM character to 00SetEndOfMessageTerminator( chFTP, 0x00 );nStatus = ReceiveStrTable( nStatus, 0, stList, chFTP );

if ( nStatus == 0 ) then

Optional: parses each listing into separated tables for: 1. date/time stamp (first 17 characters)2. file size (next 21 characters)3. filename (remaining characters) and removes the 0D 0A left over on the end of the filename.

for nIndex = 0 to (nFileCount - 1) step 1GetSubstring( stList[nIndex], 0, 17, stDateTimeStamps[nIndex] );GetSubstring( stList[nIndex], 18, 21, sTemp );ntSizes[nIndex] = StringToInt32( sTemp );GetSubstring( stList[nIndex], 39, 1000, stFilenames[nIndex] );

nLength = GetStringLength( stFilenames[nIndex] );GetSubstring( stFilenames[nIndex], 0, nLength - 2,

stFilenames[nIndex] );next

Further parsing could be done on the date/time stamps, depending on how those values will be used.

endifendif

endifCloseCommunication( chFTP );



IMPORTANT: Serial communication handles are used only for direct connection to serial devices. If you are connecting to serial devices through serial communication modules on the I/O unit, use a TCP communication handle instead. See page 261.

NOTE: Serial I/O units are wired to an RS-485 port on the controller and do not require serial communication handles. Communication is defined when the I/O unit is configured.

NOTE: Be sure to use a single communication handle for each of a controller's physical serial ports used with the subroutines. If two charts were to run simultaneously while sharing an open communication handle, it is possible for one serial port to transmit data (on the wire) at the same time the remote device is transmitting a response.

Serial Communication Handle Examples

To enter a serial communication handle, you can use either of the following two methods for SNAP PAC controllers.

Method 1. With this method, the value for the serial communication handle is in the format:ser:<port number>,<baud rate>,<parity>,<data bits>,<stop bits>

Here is an example of a serial communication handle value:

ser:0,115200,n,8,1 (port 0, baud rate of 115,200, no parity, 8 data bits, and 1 stop bit)


Setting Valid Values

port numberSNAP-PAC-S1: 0, 1, or 2SNAP-PAC-S2: 0, 1, 2, or 3SNAP-PAC-R1 and R2: 0

baud rate 230400, 115200, 76800, 57600, 38400, 19200, 9600, 4800, 2400, 1200, or 300

parity n, o, or e (none, odd, or even)

data bits 8 or 7

stop bits 1 or 2



Method 2. Using keywords, this method offers more flexibility. For example, use this method if you want to specify RTS / CTS on a serial port on a SNAP S-series or R-series controller. Keywords may be used in any order. Each keyword must be lowercase and followed by an equal sign and a value, with no spaces (even after commas), as shown in the following examples: ser:port=0,baud=115200,data=8,parity=n,stop=1,rts-cts=0

ser:baud=115200,data=8,parity=n,rts-cts=1,stop=1,port=0,timeout=1.5

In the Add Variable dialog box, enter the communication handle value in the Initial Value field. (Due to the long value, part of the value is hidden.)

NOTE: You must include at minimum the port number and at least one parameter. Otherwise, it will not work.

The keywords and possible values are:

Keyword Valid Values Comments

port 0, 1, 2, 3The ports available depends on the controller type. For a list of available ports, see the documentation that came with your controller.





If a parameter is not specified, the current value is used, so you should include any parameter whose current value you are not sure of.

IMPORTANT: As described earlier in this section, be sure to use PAC Manager to set the control function of any port you want to use to None. Otherwise, you will get a -20, (Resource Busy), error. For more information, see the PAC Manager User’s Guide.

Using Serial Communication Handles in Your Strategy

To use a serial communication handle in your strategy, first use the command Open Outgoing Communication. Verify that the communication handle opened by using the condition Communication Open? Then use Transmit, Transfer, and Receive commands to send or receive data as necessary. Remember to check for any errors. When you have finished sending and receiving data, use the command Close Communication to close the communication handle.

Make sure your strategy receives data promptly. Incoming serial communication is buffered up to 127 characters. If more than 127 characters come in before the strategy receives them, the additional characters are lost.

See the PAC Control Command Reference or online Help for details on using specific commands.

baud 230400, 115200, 76800, 57600, 38400, 19200, 9600, 4800, 2400, 1200, or 300

parity E, e, O, o, N ,n, 9* * A value of 9 is used for RS-485 multi-drop com-munications.

data 8, 7 The number of data bits

stop 1, 2 The number of stop bits

mode 0, 522* * 522 enables I/O mode. 0 should be used for everything else.

rts-cts 0, 1* * Enables symmetrical rts-cts flow control.

timeout float, seconds

Keyword Valid Values Comments

CONTROL ENGINE COMMANDS


Control Engine CommandsThe following commands refer to the control engine:

Commands Relating to Permanent StorageThe term “Permanent Storage” in the last three commands listed above refers to the control engine’s flash memory. Files that are saved to flash memory remain in the control engine even when power to it is turned off.

These commands do NOT affect firmware files, configuration data, or strategy files saved to flash; they affect only files at the root of the control engine’s file system. For more information on the file system, see “Using the Control Engine’s File System” on page 269. For the specifics on individual commands, see online help or the PAC Control Command Reference.

CAUTION: Since these commands write to flash memory, use them sparingly within your strategy and make sure they do not end up in a loop. You can literally wear out flash memory if you save to it or erase it too many times.

Calculate Strategy CRC Get Firmware Version

Erase Files In Permanent Storage Load Files From Permanent Storage

Get Available File Space Retrieve Strategy CRC

Get Control Engine Address Save Files To Permanent Storage

Get Control Engine Type Start Alternate Host Task



Digital Point CommandsThe following commands are used with digital points.

States, Latches, and CountersThe following diagram illustrates states, latches, and counters. While states and latches apply to digital points on all I/O units, counters depend on the capability of the brain. See the brain’s data sheet for specifications.

Basic Commands Latches

Off? Clear All Latches

On? Clear Off-Latch

Turn Off Clear On-Latch

Turn On Get Off-Latch

Get On-Latch

Totalizers Get & Clear Off-Latch

Get Off-Time Totalizer Get & Clear On-Latch

Get On-Time Totalizer Off-Latch Set?

Get & Restart Off-Time Totalizer On-Latch Set?

Get & Restart On-Time Totalizer

Pulses

Counters* Generate N Pulses

Clear Counter Get Off-Pulse Measurement

Get Counter Get Off-Pulse Measurement Complete Status

Get & Clear Counter Get & Restart Off-Pulse Measurement

Start Counter Get On-Pulse Measurement

Stop Counter Get On-Pulse Measurement Complete Status

Get & Restart On-Pulse Measurement

Period and Frequency Start Continuous Square Wave

Get Frequency Start Off-Pulse

Get Period Start On-Pulse

Get Period Measurement Complete Status

Get & Restart Period

Set TPO Percent

Set TPO Period

*Some digital point commands are available in PAC Control Professional only. Some commands are available only on some I/O units. For details, see specific information for each command in the PAC Control Command Reference or online Help.

DIGITAL POINT COMMANDS


Latches

Latches are an extremely high-speed digital function. Both on-latches and off-latches are available. Latches are automatic and do not have to be configured.

When the value of a digital input point changes from off to on, an on-latch is automatically set. While the value of the point may return to off, the on-latch remains set until cleared, as a record of the change. Similarly, an off-latch is set when the value of a digital point changes from on to off, and it remains set until cleared.

To read a latch and clear it at the same time, use the command Get & Clear On-Latch or Get & Clear Off-Latch.

Counters

Most standard digital inputs can be used as counters to count the number of times the input changes from off to on. The availability of counters depends on the brain’s capabilities, and the speed of counters depends on the module; see the brain’s and module’s data sheets for specifications.

NOTE: You can use counters on high-density modules with SNAP-PAC-R1 controllers and SNAP-PAC-EB1 and SNAP-PAC-SB1 brains with firmware 8.1 or newer.

Before using a counter, you must configure the point as a counter. (See “Adding a Digital I/O Point” on page 128 or use PAC Manager.) Counters do not need to be started, and they cannot be stopped. Therefore, do not use the Start Counter and Stop Counter commands. However, you can use Get Counter and Get & Clear Counter.



Quadrature Counters

Quadrature counters require a special module and configuration, but once they are configured, you use the same commands (such as Start Counter and Clear Counter) for them as for regular counters.

NOTE: You can use counters on high-density modules with SNAP-PAC-R1 controllers and SNAP-PAC-EB1 and SNAP-PAC-SB1 brains with firmware 8.1 or newer.

Before using a counter, you must configure the point as a counter. (See “Adding a Digital I/O Point” on page 128 or use PAC Manager.) Counters do not need to be started, and they cannot be stopped. Therefore, do not use the Start Counter and Stop Counter commands. However, you can use Get Counter and Get & Clear Counter. A positive value means that phase A leads phase B. See additional details in the PAC Control Command Reference or online Help.

Totalizers Digital totalizers track the total time a specific input point has been on or off. For example, you could track how long a pump, fan, or motor has been on. Digital totalizers are useful for periodic maintenance. Before using a totalizer, you must configure the point with this feature. (See “Adding I/O Points” on page 128 for help.) The availability of totalizers depends on the brain; see the brain’s data sheet for more information.

To check total time and leave the totalizer running, use Get Off-Time Totalizer or Get On-Time Totalizer. To check total time and reset the totalizer to zero, use Get & Restart Off-Time Totalizer or Get & Restart On-Time Totalizer.

Pulses Pulsing commands send on- and off-pulses to an output point. The availability of pulsing depends on the brain; see the brain’s data sheet for specifications.

Generate N Pulses . The command Generate N Pulses is frequently used to flash a light or sound an alarm. For example, you could sound a two-second alarm four times. In the arguments, you set the number of times the on-pulse is sent, the length of the on-pulse, and the length of the off-pulse. Generate N Pulses always starts with an off-pulse. If you resend this command, make sure to leave sufficient time in between so it does not interfere with itself.

Start On Pulse and Start Off Pulse . The commands Start On Pulse and Start Off Pulse send a single pulse cycle:

• Start On Pulse starts with an on-pulse of a length you determine, and ends with an off-pulse.

• Start Off Pulse starts with an off-pulse of a length you determine, and ends with an on-pulse.

DIGITAL POINT COMMANDS


Both of these commands can be used as time delays. For example, if a light is on and you want to turn it off after 30 seconds, you can send a Start On Pulse command, setting the on-pulse to be 30 seconds long. At the end of that time, the off-pulse is sent to turn off the light.

You can also use this type of command in a loop to turn a digital point on or off for short intervals. For example, you could create a loop that checks the level of liquid in a tank and pulses on a drain if the level is too high. The advantages of using a pulse command are that the point does not have to be turned off, and if communication is lost to the point, the point does not remain on.

Pulse Measurement commands measure pulses on digital input points. For details, see the specific command in the PAC Control Command Reference or online Help.

IVAL and XVAL All I/O points have two associated values: XVAL and IVAL. If you are using PAC Control in Debug mode to manipulate I/O values or to disable an I/O point or I/O unit, you need to understand these values.

XVAL. The external value, or XVAL, is the “real” or hardware value as seen by the I/O unit. This value is external to the control engine and strategy logic.

IVAL. The internal value, or IVAL, is a logical or software copy of the XVAL that is in the control engine. The IVAL may or may not be current, since it is updated to match the XVAL when strategy logic accesses the I/O point.

If the IVAL does not match the XVAL, a mismatch just means that your strategy logic is not reading from or writing to the I/O point in question at the moment.

Simulation and Test: The “Real” Use for XVAL and IVAL

To test output performance, you may want to force an XVAL for a specific output to a particular value. If the program is actively writing to the output, you need to disable the output to do so. If the program is stopped, there is no need to disable it.

To test program logic, you may want to force an IVAL for a specific input to a particular value. To do so, you must disable the input first.

You can disable an I/O point or unit in two ways. The more common way is from within Debug mode, by double-clicking a point on the Strategy Tree and modifying the point’s settings and values through the Inspection dialog box. The second way is from within the strategy, using commands such as Disable Communication to Digital Point, Disable Communication to Analog Point, or Disable Communication to I/O Unit. (See “Simulation Commands” on page 308.)



Additional Commands to Use with Standard Digital PointsAlthough not listed under Digital Point commands, several other commands can be used for digital operations:

• Use Move to cause an output to assume the state of another input or output. A digital input or output that is on returns a True (non-zero). A True (non-zero) sent to a digital output turns it on.

• Use NOT to cause an output on one I/O unit to assume the opposite state of an input on another I/O unit.

• Use Get I/O Unit as Binary Value to get the state of all points at once. Then use Bit Test to determine the state of individual points. This method is much faster than reading each point individually.

• Use Set I/O Unit From MOMO Masks to control all outputs at once.

Standard Digital Points and OptoScript CodeIn OptoScript code, a standard digital I/O point can be used directly, wherever a numeric variable can be used. For example, you can turn a point off by assigning it a value of zero, or turn it on by assigning it a non-zero value. You can also use standard digital points directly in mathematical expressions and control structures. For more information, see “Using I/O in OptoScript” on page 331.

ERROR HANDLING COMMANDS


Error Handling CommandsThe following commands refer to handling errors:

All good programmers must deal with errors. These error handling commands are used to monitor errors, figure out which I/O unit caused an error, disable or re-enable communicatin to the I/O unit, and clear errors and other messages from the message queue. For a simple example of an error handler chart, see page 86. For more on the message queue, see “Queue Messages” on page 380.

You can use the command Add User Error to Queue to add your own information, warning, or error message to the queue. This command can be helpful in troubleshooting.

IO Enabler Sample StrategiesSample “IO Enabler” strategies are available on the Opto 22 website. The logic in these sample strategies is designed to automatically recover communications to any I/O unit that temporarily goes offline (that is, has communications disabled) for any reason. Choose a sample that is compatible with your system configuration. Each sample has the same basic code:

www.opto22.com/site/downloads/dl_drilldown.aspx?aid=3605



Add Message to Queue Get Error Code of Current Error

Add User Error to Queue Get Error Count

Add User I/O Unit Error to Queue Get ID of Block Causing Current Error

Caused a Chart Error? Get Line Causing Current Error

Caused an I/O Unit Error? Get Name of Chart Causing Current Error

Clear All Errors Get Name of I/O Unit Causing Current Error

Copy Current Error to String Get Severity of Current Error

Disable I/O Unit Causing Current Error Remove Current Error and Point to Next Error

Enable I/O Unit Causing Current Error Stop Chart on Error

Error on I/O Unit? Suspend Chart on Error

Error?



I/O Unit CommandsThe following commands are used to communicate with an I/O unit, which controls a group of I/O points:

CAUTION: Write I/O Unit Configuration to EEPROM is not the recommended method for saving configuration to flash memory. If it is used too often or is in a loop within a strategy, flash memory can literally wear out. Instead of using this command in the strategy, it is better to store configurations to flash manually using either PAC Manager (see the PAC Manager User’s Guide for instructions) or PAC Control in Debug mode (see “Inspecting I/O Units and Saving Settings to Flash” on page 148).

Commands for Ethernet Link Redundancy The three target address commands (Get Target Address State, Set Target Address State, and Set All Target Address States) are used to manually change the path of communication between the controller and the I/O unit(s), based on the IP address used for the I/O unit. These commands let you switch communication from a primary to a secondary IP address (or vice versa) or enable or disable communication to the primary or secondary address.

Ethernet link redundancy to I/O units is available only in PAC Control Professional. The secondary IP address for an I/O unit may be for the second Ethernet network interface on a SNAP PAC R-series controller, or it may be for a separate I/O unit. If it is a separate unit, the primary and secondary I/O units must be the same type (for example, SNAP-PAC-EB1) and have exactly the same points, because they are configured together under one name.

One or both target addresses (primary and secondary) can be enabled, but only one address (the active address ) will be used by the controller at one time. For link redundancy, both the primary and secondary addresses must be enabled. When an I/O unit is configured with two IP addresses, the default is for both to be enabled and the primary address to be active.

One address is always active. If communication fails through the primary address, the control engine automatically switches to the secondary address. It continues to use the secondary address until communication fails through the secondary address or until you change the active address using Set Target Address State (for one I/O unit) or Set All Target Address States (for all I/O units on the control engine).

Clear I/O Unit Configured Flag Move I/O Unit to Numeric Table Ex

Get I/O Unit as Binary Value Move Numeric Table to I/O Unit

Get I/O Unit as Binary Value 64 Move Numeric Table to I/O Unit Ex

Get Target Address State1 Set All Target Address States1

I/O Unit Ready? Set I/O Unit Configured Flag

IVAL Move Numeric Table to I/O Unit Set Target Address State1

IVAL Move Numeric Table to I/O Unit Ex Write I/O Unit Configuration to EEPROM

Move I/O Unit to Numeric Table1 PAC Control Professional only

I/O UNIT COMMANDS


You may also want to use these commands to disable one address, for example if you are doing maintenance or repair on a network segment and need to switch communication to another segment temporarily. Disabling one address, of course, means that you no longer have link redundancy.

If both addresses are disabled or unavailable, then communication is not possible and communication to the I/O unit becomes disabled. If both addresses are disabled, and you want to bring the I/O unit back online, you must first enable one or both of the addresses and then enable communication to the I/O unit.

You can find out which addresses are enabled for an I/O unit and which address is currently active by using Get Target Address State. If an address is enabled but is not functional when a strategy is started or when communication for an I/O unit is changed from Disabled to Enabled, an error is posted in the controller’s error queue.

To use these commands, you must have already designated primary and secondary IP addresses when configuring I/O units. For steps, see “Adding an I/O Unit” on page 122. For additional information about link redundancy, see “Using Ethernet Link Redundancy in PAC Control” on page 102.

Table CommandsThe table commands for I/O units affect the states or values of all points on the I/O unit at once. For example, you can use the command Move I/O Unit to Numeric Table to read the states of all digital points and the values of all analog points on one I/O unit and place them into a table for easy retrieval. Table commands move data very quickly for faster throughput.

Three of the table commands—IVAL Move Numeric Table to I/O Unit Ex, Move I/O Unit to Numeric Table Ex, and Move Numeric Table to I/O Unit Ex—provide support for high-density points. A Points per Module parameter lets you specify the number of points required. For example, if you are using 32-channel modules, you would pass a 32. But if you are only using 8-channel modules, you could pass an 8 instead. This allows table sizes to be as small as possible.

Other commands relating to tables can be found in the following topics:

“Miscellaneous Commands” on page 301“Logical Commands” on page 295“Mathematical Commands” on page 297“Pointer Commands” on page 306“String Commands” on page 309.



I/O Unit—Event Message CommandsThe following commands refer to event messages sent from SNAP PAC I/O units.

A SNAP PAC I/O system can send a message as a response to an event that occurs within strategy logic. For example, if pressure in a pipe reaches a certain level, the system can send a warning email message to a technician. Or data about a process can be streamed to a computer every 30 seconds for monitoring.

CAUTION: Events and reactions, including event messages, that are processed separately from your strategy can conflict with strategy logic. If you are using PAC Control, use strategy logic instead of local events and reactions on the I/O unit, or be very careful that local events and reactions do not conflict.

Use PAC Manager to configure event messages, following the steps in Opto 22 form 1704, the PAC Manager User’s Guide. You can configure the following types of event messages:

• Email or paging messages sent to a person

• Simple Network Management Protocol (SNMP) traps sent to an enterprise management system

• Serial messages sent through a serial communication module to a serial device

• Streamed data sent to a device for processing by a software application.

I/O Unit—Event Message commands are commonly used to find out the state or text of an event message, or to set its state. Event messages can be in the following states:

• Active—The message has been triggered by the event. If it was configured to be sent just once, it has been sent. If it was configured to be sent at intervals, it is continuing to be sent.

• Inactive—The message is not currently triggered by the event.

• Acknowledged—The message has been triggered by the event but has been acknowledged by the receiver so it will not be sent again. (Acknowledgments occur only if the receiving application writes them to the brain’s memory map.) Acknowledged is functionally equivalent to Inactive, but can be useful in some cases to determine whether the receiver has received the message.

The command Set I/O Unit Event Message Text is used to dynamically change a message or to “recycle” a message if you run out of event messages on an I/O unit (128 event messages are available for each I/O unit). For more information, see individual commands in the PAC Control Command Reference or online help.

Get I/O Unit Event Message State

Get I/O Unit Event Message Text

Set I/O Unit Event Message State

Set I/O Unit Event Message Text

I/O UNIT—MEMORY MAP COMMANDS


I/O Unit—Memory Map CommandsThe following commands refer to the memory map in an Opto 22 memory-mapped device, either a controller or an I/O unit. In the case of a controller/brain, they can refer to the device’s own memory map or a memory map on another device.

Memory map commands make it possible for advanced users to read from or write to any Opto 22 memory-mapped device, such as a SNAP PAC controller or brain. You can use these commands to read or write to any address within the memory map. The commands are especially useful for reading data from a SNAP device using newer features that may be available in the memory map but are not yet incorporated into PAC Control.

NOTE: If you are reading or writing to the device’s Scratch Pad area, use the I/O Unit—Scratch Pad commands instead (see page 293). If you are changing event messages, use the I/O Unit—Event Message commands instead (page 291).

Before you use these commands with a SNAP-PAC-S1, you must have already configured an I/O unit to represent the controller. Configure the controller as a Generic Memory Map Device with the IP address of the control engine.

When you use these commands, make sure that you read or write the correct type of data (integer, float, string) to match the specified memory map address. The control engine doesn’t know what type of data is in any particular address, so it cannot convert the data type.

Since these are I/O unit commands, remember to check all return values and errors to make sure the command was successful. If a command variable contains a value that is obviously wrong—for example, a memory map address in an incorrect format—communication to the I/O unit will be automatically disabled.

See the OptoMMP Protocol Guide (Opto 22 form 1465) to determine the memory map addresses and data types you need to use.

Read Number from I/O Memory Map

Read Numeric Table from I/O Memory Map

Read String from I/O Memory Map

Read String Table from I/O Memory Map

Write Number to I/O Memory Map

Write Numeric Table to I/O Memory Map

Write String Table to I/O Memory Map

Write String to I/O Memory Map



I/O Unit—Scratch Pad CommandsThe following commands are used for peer-to-peer communication for sharing strategy data with other Opto 22 memory-mapped controllers on the network. These commands are used by PAC Control to read or write to the Scratch Pad area in the memory map of a SNAP PAC controller.

Since each read (get) or write (set) command is completed before another occurs, commands cannot interfere with each other. For example, a get command won’t read a partial string while a set command is writing the string.

Since these are I/O unit commands, when they are used for a SNAP-PAC-S1, you must have already configured an I/O unit to represent the controller. Configure the controller as a Generic Memory Map Device with the IP address of the control engine.

Also because these are I/O unit commands, remember to check all return values and errors to make sure the command was successful. If a command variable contains a value that is obviously wrong—for example, a memory map address in an incorrect format—communication to the I/O unit will be automatically disabled.

Each controller running a PAC Control strategy can place data in its own or another’s Scratch Pad area, and each can retrieve data that has been placed in the Scratch Pad area by other devices using other applications. Using these commands eliminates the need to open communication handles (see “Communication Commands” on page 259), thus speeding up peer-to-peer communication.

The memory map Scratch Pad area supports four data types: bits, integer 32s, floats, and strings.

• For details on the Scratch Pad area, see Opto 22 form 1704, the PAC Manager User’s Guide.

• For the complete memory map, see form 1465, the OptoMMP Protocol Guide.

• For details on using the Scratch Pad for peer-to-peer communication with a controller, see the controller’s user’s guide.

The following page shows a simple example of how Scratch Pad area data exchange would work between two SNAP R-series I/O systems.

Create two tables for PAC_R_A, one for its own data that will be shared (A_Shared_Data) and another for data it will read from PAC_R_B (B_Data). Also create two tables for PAC_R_B, one for its own data (B_Shared_Data) and one for PAC_R_A’s data (A_Data).

Get I/O Unit Scratch Pad Bits Set I/O Unit Scratch Pad Bits from MOMO Mask

Get I/O Unit Scratch Pad Float Element Set I/O Unit Scratch Pad Float Element

Get I/O Unit Scratch Pad Float Table Set I/O Unit Scratch Pad Float Table

Get I/O Unit Scratch Pad Integer 32 Element Set I/O Unit Scratch Pad Integer 32 Element

Get I/O Unit Scratch Pad Integer 32 Table Set I/O Unit Scratch Pad Integer 32 Table

Get I/O Unit Scratch Pad String Element Set I/O Unit Scratch Pad String Element

Get I/O Unit Scratch Pad String Table Set I/O Unit Scratch Pad String Table

I/O UNIT—SCRATCH PAD COMMANDS


This portion of the flowchart in PAC_R_A (without error checking) might look like this:

Meanwhile, PAC_R_B writes data from its B_Shared_Data table to its Scratch Pad area, which PAC_R_A reads.

PAC Control Tables:

Integer elements0-599

A_Shared_Data(indexes 0-599)

Memory Map Scratch Pad:PAC Control Tables:A_Data

Integer elements0-599

PAC_

R_A

PAC_

R_B

Memory Map Scratch Pad:

Suppose PAC_R_A and PAC_R_B are sharing 600 integer elements of the 10,240 integer elements available in the Scratch Pad

PAC_R_A writes data from its own PAC Control strategy table to its own Scratch Pad area, which SPAC_R_B can then read.

NOTE: When the SNAP R-series I/O unit is writing to its own Scratch Pad, use the

B_Data

B_Shared_Data(indexes 0-599)

As you can see, PAC_R_A uses the Set I/O Unit Scratch Pad command to write the data from its own table to its own memory map. PAC_R_A also reads data from PAC_R_B’s memory map and places it in table B_Data.

A similar flowchart would be in PAC_R_B’s strategy, to handle writing to its own Scratch Pad area and reading from PAC_R_A.



Logical CommandsThe following commands perform logical functions:

Understanding Logical CommandsFor condition blocks, the Instructions dialog box provides options to designate AND or OR for multiple commands. If you have more than one command in the same condition block and you choose the AND option, all of the commands must evaluate true for the block to exit true. If you have more than one command in a condition block and choose the OR option, the block exits true if any of its commands evaluates true.

Logical actions and conditions work with integers, individual bits within an integer, a single digital I/O point, or a digital I/O unit. These values are treated as Boolean; that is, they are either True or False.

For complex logical operations, you may find OptoScript code easier to use than standard PAC Control commands. See “Using Logical Operators” on page 341 for more information.

AND Less Than or Equal to Numeric Table Element?

AND? Less Than or Equal?

Bit AND Less?

Bit AND? Make Integer 64

Bit Clear Move 32 bits

Bit NOT NOT

Bit NOT? Not Equal to Numeric Table Element?

Bit Off in Numeric Table Element? Not Equal?

Bit Off? NOT?

Bit On in Numeric Table Element? Numeric Table Element Bit Clear

Bit On? Numeric Table Element Bit Set

Bit OR Numeric Table Element Bit Test

Bit OR? OR

Bit Rotate OR?

Bit Set Set Variable False

Bit Shift Set Variable True

Bit Test Test Equal

Bit XOR Test Greater

Bit XOR? Test Greater or Equal

Equal to Numeric Table Element? Test Less

Equal? Test Less or Equal

Get High Bits of Integer 64 Test Not Equal

Get Low Bits of Integer 64 Test Within Limits

Greater Than Numeric Table Element? Variable False?

Greater Than or Equal to Numeric Table Element? Variable True?

Greater Than or Equal? Within Limits?

Greater? XOR

Less Than Numeric Table Element? XOR?

LOGICAL COMMANDS


Logical True and Logical False

PAC Control always returns a value of +1 to indicate True in an integer variable.

A digital input or output that is on also returns a True (+1). Any non-zero value sent to a digital output turns it on. False is defined as zero (0).

For individual bits within an integer variable, bits that are set (1) indicate on. Bits that are cleared (0) indicate off.

While floats can be used in logic, integers are strongly recommended whenever any bits are referenced. Since PAC Control does not permit bits in a float value to be altered, float values must be converted to integers before bits can be evaluated. See “Mathematical Commands” on page 297 for further information on integers and floats.



Mathematical CommandsThe following commands perform mathematical functions:

Using IntegersIn PAC Control, an integer 32 is a 32-bit signed number ranging from -2,147,483,648 to 2,147,483,647 (±2 billion). An integer 64 ranges from -9,223,372,036,854,775,808 to 9,223,372,036,854,775,807.

An integer can only be a whole number (-1, 0, 1, 2, 3, etc.). In other words, integers do not include a decimal point. The result of an integer operation is always an integer, even if it is placed in a float variable. For example, if 9 is divided by 10, the result is zero (0.9 truncated to an integer). To receive a float result, at least one of the operators would have to be a float. Use the Truncate command to round down to the nearest whole number.

Controlling Rounding

Use the Round command to round up or down to the nearest whole number. Note that 1.50 rounds up to 2.0, and 1.49 rounds down to 10.

Using FloatsWhile computers, CPUs, and electronic devices (such as Opto 22 controllers) store numbers in binary format, most often they represent real numbers as floating point numbers, or floats. For example, in industrial automation applications, all analog values read from an I/O unit are floats. Floats represent real numbers in scientific notation: as a base number and an exponent.

Absolute Value Raise to Power

Add Round

Clamp Float Table Element Seed Random Number

Clamp Float Variable Square Root

Clamp Integer 32 Table Element Subtract

Clamp Integer 32 Variable Truncate

Complement

Decrement Variable Trigonometry

Divide Arcsine

Generate Random Number Arccosine

Increment Variable Arctangent

Maximum Cosine

Minimum Hyperbolic Cosine

Modulo Hyperbolic Sine

Multiply Hyperbolic TangentSine

Natural Log Tangent

Raise e to Power

MATHEMATICAL COMMANDS


The IEEE Standard for Binary Floating-Point Arithmetic (IEEE 754) is the most widely used standard for floating-point computation. It defines how to store real numbers in binary format and how to convert between binary and float notations.

Opto 22’s SNAP PAC System uses IEEE single-precision floats, which have 32 binary digits (bits). The IEEE 754 32-bit float format is as follows:

Float calculation: (-1)Sign x [1 + Significand/223] x 2 (Exponent-127)

While this is an excellent standard for the purpose, it has limitations that could cause issues if you’re not aware of them. Squeezing infinitely many real numbers into a finite number of bits requires an approximate representation. Most floats cannot be exactly represented using this fixed number of bits in a 32-bit IEEE float. Because of this, rounding error is inherent in floating-point computation.

In PAC Control (and in PAC Manager and the OptoMMP protocol), a float is a 32-bit IEEE single-precision number ranging from ±3.402824 x 10-38 to ±3.402824 x 10+38. These single-precision floats give rounding errors of less than one part per million (1 PPM). You can determine the limit of the rounding error for a particular float value by dividing the value by 1,000,000.

This format guarantees about six and a half significant digits. Therefore, mathematical actions involving floats with seven or more significant digits may incur errors after the sixth significant digit. For example, if the integer 555444333 is converted to a float, the conversion yields 5.554444e+8 (note the error in the 7th digit). Also, converting 5.554444e+8 back to an integer yields 555444352 (note the error starting in the 7th digit).

Float Issues and Examples

Accumulation of Relatively Small Floating-point Values. When adding float values, the relative size of the two values is important. For example, if you add 1.0 to a float variable repeatedly, the value of the float variable will correctly increase in increments of 1.0 until it reaches 1.677722e+7 (16,777,220).

Then the value will no longer change, because 1.0 is too small relative to 1.677722e+7 to make a difference in the significant digits. The same thing will occur if you add 0.0001 to 2,048.0, or add 1,000.0 to 1.717987e+10. The key is the relative size of the numbers.

Here’s another way to think of it. Suppose your bank could only keep track of seven digits. If you were fortunate enough to have one million dollars ($1,000,000) in your account and tried to add 10 cents ($0.10) to it, you would not be able to, because the 10 cents is not big enough relative to the total to be significant. Since the bank has only seven digits to keep track of your money (in this example), one digit has to fall off the end: either the 10 cents

1 bit 8 bits 23 bits

x xxxxxxxx xxxxxxxxxxxxxxxxxxxxxxx

Sign Exponent Significand



falls off the right side or the million digit falls off the left side. Which would you rather see in your bank account?

Note that moving the point indicator doesn’t help, because the exponent is separate. If the seven digits for the account represent millions of dollars (1.000000) rather than dollars (1,000,000), the 10 cents would be 0.0000001—still too small to be represented by the seven digits:

The key is that it is not the size of the numbers that matter, but rather their relative size.

So if you are accumulating relatively small values in a float variable over a long period of time, at some point, the float value will stop increasing even though you continue to try to add to it.

Comparing Floating-point Values for Equality. Due to rounding errors and the way floating-point calculations are performed, comparing two floats for equality can yield inaccurate results. The precision of comparisons depends on the relative size of the float values as compared to the difference between them.

For example, if 2,097,151.0 is compared for equality with 2,097,152.0, the result will indicate that the two floats are equal, even though it’s obvious they are not. The reason is that the difference between the two values is 1.0, and 1.0 compared to one of the compared values (2,097,151.0) is too small; it is less than one part per million.

In this case, 2,097,152.0 divided by 1,000,000 is 2.1. If the difference between the two values is at least 2.1, then the equality comparison is guaranteed to be correct. So if 2,097,152.0 and 2,097,149.0 were compared for equality, the result will indicate they are not equal, because the difference (3.0) is greater than one part per million (2.1). Any time the difference is at least one part per million, the result is guaranteed to be accurate. If the difference is less than 1 PPM, it may or may not be accurate.

One method that programmers use to work around this issue is to subtract one float from the other and then compare the absolute value of the result to a limit.

For example:Float_Diff = Float1 - Float2;If (AbsoluteValue(Float_Diff) < 1.0 ) then SetVariableTrue(EqualityFlag);Else SetVariableFalse(EqualityFlag);Endif

Seven digits available: 1 2 3 4 5 6 7

Amount in account: 1 0 0 0 0 0 0

Add 10 cents (0.10)? (digit falls off on right) 1 0 0 0 0 0 0

Add 10 cents (0.10)? (digit falls off on left) 0 0 0 0 0 0. 1 Oops!

Seven digits available: 1 2 3 4 5 6 7

Amount in account 1. 0 0 0 0 0 0

Add 10 cents (0.0000001)? (digit falls off on right) 1. 0 0 0 0 0 0

Add 10 cents (0.0000001)? (digit falls off on left) .0 0 0 0 0 0 1 Oops again!

MATHEMATICAL COMMANDS


Helpful Links for More Information

From Wikipedia, the free encyclopedia: http://en.wikipedia.org/wiki/IEEE_754

Real numbers: http://en.wikipedia.org/wiki/Real_number

Good example: http://en.wikipedia.org/wiki/Single_Precision

Rounding error: http://docs.sun.com/source/806-3568/ncg_goldberg.html

Comparing floating point numbers: http://www.cygnus-software.com/papers/comparingfloats/comparingfloats.htm

Mixing and Converting Integers and FloatsAn analog value read from an I/O unit and put into an integer is converted from float to integer automatically.

To maintain the integrity and accuracy of a numeric type (float or integer), keep all item types the same. For example, use the Move command to copy an integer value to a variable float when you want float calculations.



Miscellaneous CommandsThe following commands are used with tables and for other purposes. Many of them are commonly used.

Comment CommandsThe comment commands listed above are used with standard PAC Control commands in action blocks and condition blocks. For information on using comments in OptoScript blocks, see step 10 in “Using the OptoScript Editor” on page 346.

Comment (Single Line) and Comment (Block) commands are used in two entirely different ways:

• Comment (Single Line) enters a comment to help explain a block or an instruction within a block. Usually block names and comments within instructions are sufficient, but you can use Comment (Single Line) if you need more room for explanations.

• Comment (Block) comments out instructions. In other words, it tells the strategy to temporarily ignore certain instructions within a block. It can be useful in debugging or for saving work when a strategy is temporarily changed.

To use it, place one Comment (Block) command at the beginning of the area you want to ignore, and place another Comment (Block) command at the end of the area. If you do not place the second Comment (Block) command, all the remaining instructions in that block are ignored. Areas that are commented out appear in the Instructions dialog box as gray.

Comment (Block) Get Value From Name

Comment (Single Line) Move

Flag Lock Move from Numeric Table Element

Flag Unlock Move Numeric Table Element to Numeric Table

Float Valid? Move Numeric Table to Numeric Table

Generate Reverse CRC-16 on Table (32 bit) Move to Numeric Table Element

Get Length of Table Move to Numeric Table ElementsShift Numeric Table Elements

Get Type From Name

PID—ETHERNET COMMANDS


PID—Ethernet CommandsThe following commands are used with PID loops on SNAP PAC I/O units. Since PID loops are configured and tuned in Configure Mode while creating your PAC Control strategy, you may not need to use these commands. PID commands are typically used to change input or output location (for example, if the input is on another I/O unit) or to change tuning parameters based on a change that occurs while the strategy is running (such as a recipe change).

For steps to configure and tune PIDs, see “Configuring PID Loops” on page 141. For more information about PID loops, how to tune them, and how to use them in PAC Control, see Opto 22 form 1641, OptoTutorial: SNAP PAC PID.

What is a PID?A proportional integral derivative (PID) control system (often referred to as a PID loop) monitors a process variable, compares the variable’s current value to a desired value (a setpoint), and calculates an output to correct error between the setpoint and the variable. Because the calculation is complex, it is done by a mathematical formula that is adjusted (tuned) for each PID loop. The mathematical formulas vary, but all PID systems share these fundamental concepts:

• They evaluate a process variable against its setpoint.

• They control an output to correct the process variable.

• The output comprises proportional, integral, and derivative calculations.

Get PID Configuration Flags Get PID Tune Derivative

Get PID Current Input Get PID Tune IntegralSet PID Configuration Flags

Get PID Current Setpoint Set PID Feed Forward

Get PID Feed Forward Set PID Feed Forward Gain

Get PID Feed Forward Gain Set PID Forced Output When Input Over Range

Get PID Forced Output When Input Over Range Set PID Forced Output When Input Under Range

Get PID Forced Output When Input Under Range Set PID Gain

Get PID Gain Set PID Input

Get PID Input Set PID Input High Range

Get PID Input High Range Set PID Input Low Range

Get PID Input Low Range Set PID Max Output Change

Get PID Max Output Change Set PID Min Output Change

Get PID Min Output Change Set PID Mode

Get PID Mode Set PID Output

Get PID Output Set PID Output High Clamp

Get PID Output High Clamp Set PID Output Low Clamp

Get PID Output Low Clamp Set PID Scan Time

Get PID Scan Time Set PID Setpoint

Get PID Setpoint Set PID Tune Derivative

Get PID Status Flags Set PID Tune Integral



• The effect of proportional, integral, and derivative calculations is modified by user-determined P, I, and D constants.

• The P, I, and D constants need to be tuned for each system.

PID Loops on I/O UnitsSNAP PAC controllers and brains provide 96 PID loops per I/O unit. Because PIDs run on the I/O side of the SNAP PAC R-series controller, not on the control side, these PIDs will keep running on the SNAP PAC R-series I/O unit even if the PAC Control strategy stops.

In PAC Control, you can configure each of the PID loops with unique settings for a large number of parameters. For a simple PID loop, you must configure at least the following:

• Input (the process variable being monitored)

• Setpoint (the desired value)

• Output (the I/O point that effects change in the system)

• Scan time (how often the input is sampled)

• PID algorithm used (four algorithms are available; see “Algorithm Choices (PID)” on page 303.

• Valid range for input

• Upper and lower clamps for output

• Minimum and maximum change for output

You can also configure the following parameters if necessary:

• Forced output value or use of manual mode if input goes out of range

• Feed forward gain

• Square root of input

In the SNAP PAC, the derivative is applied only to the process variable (the input) and not to the setpoint. This means you can change the setpoint without causing spikes in the derivative term. These PIDs also prevent integral windup by back calculating the integral without the derivative term. The feed forward term (“bias”) is added before output clamping and has a tuning factor.

If desired, you can cascade PIDs by simply using the output point of one PID loop as the input point for another.

Algorithm Choices (PID)When you configure a PID loop in PAC Control, choose one of the following algorithms:

• Velocity - Type C

• Velocity - Type B

• ISA

PID—ETHERNET COMMANDS


• Parallel

• Interacting

The only difference between Velocity - Type C and Velocity - Type B is the Term P equation (see equations below). The ISA, Parallel and Interacting algorithms are functionally equivalent; the only difference is the way the tuning constants are factored. The identical and differing equations for all algorithms are shown in the following sections.

Key to Terms Used in Equations

Equations Common to All AlgorithmsErr = PV - SPSpan = (OutHi - OutLo) / (InHi - InLo)Output = Output + FeedForward * TuneFF

Velocity - Type C AlgorithmTermP = ( PV - PV1 )TermI = TuneI * ScanTime * ErrTermD = TuneD / ScanTime * ( PV - 2 * PV1 + PV2 )ΔOutput = Span * Gain * ( ΔTermP + ΔTermI + ΔTermD )Velocity - Type B AlgorithmTermP = ( Err - Err_1 )TermI = TuneI * ScanTime * ErrTermD = TuneD / ScanTime * ( PV - 2 * PV1 + PV2 )ΔOutput = Span * Gain * ( ΔTermP + ΔTermI + ΔTermD )Non-velocity AlgorithmsThese equations were derived from the article “A Comparison of PID Control Algorithms” by John P. Gerry in Control Engineering (March 1987). These three equations are the same except for the tuning coefficients; converting from one equation to another is merely a matter of converting the tuning coefficients.

Equations common to all but the velocity algorithm: Integral = Integral + ErrTermP = ErrTermI = TuneI * ScanTime * IntegralTermD = (TuneD / ScanTime) * ( PV - PV1 )

PV Process variable; the input to the PID TuneD

Derivative tuning parameter. In units of seconds. Increasing magnitude increases influence on output.

SP Setpoint Output Output from the PID

InLo, InHi

Range of the input Err_1The Error (PV – SP) from the previ-ous scan

OutLo, OutHi

Range of the output IntegralIntegrator. Anti-windup is applied after the output is determined to be within bounds.

GainProportional tuning parameter. Unitless. May be negative. PV1, PV2

PV from the previous scan and the scan before that.

TuneIIntegral tuning parameter. In units of seconds. Increasing magnitude increases influence on output.

ScanTimeActual scan time (time since previ-ous scan)



“Ideal” or ISA AlgorithmOutput = Span * Gain * ( TermP + TermI + TermD )

“Parallel” Algorithm: Output = Span * ( Gain * TermP + TermI + TermD )

“Interacting” Algorithm: Output = Span * Gain * ( TermP + TermI ) * ( 1 + TermD )

POINTER COMMANDS


Pointer CommandsThe following commands are used with pointers:

See also:

“Understanding Pointers” on page 306

“Advantages of Using Pointers” on page 307

“Referencing Objects with Pointers” on page 307

Understanding PointersLike integer and float variables, a pointer variable stores a specific number. However, the number is not data—it is the memory location (address) of data. The pointer “points” to data rather than containing the data.

A pointer in PAC Control can point to many different types of objects:

• Another variable

• A digital point or object

• An analog point or object

• An I/O unit

• A chart.

Pointers cannot point to other pointers, however. If you try to move a pointer to a pointer, PAC Control just duplicates the existing pointer.

The following table lists the objects that pointers can point to:

Clear Pointer Move to Pointer

Clear Pointer Table Element Move to Pointer Table

Get Pointer From Name Pointer Equal to NULL?

Move from Pointer Table Element Pointer Table Element Equal to NULL?

Digital Objects Analog Objects I/O Units Variables Other Objects

Digital InputDigital OutputCounterQuadrature Counter

Analog InputAnalog Output

SNAP-PAC-R1SNAP-PAC-R2SNAP-PAC-EB1SNAP-PAC-EB2SNAP-PAC-SB1SNAP-PAC-SB2

Integer VariableFloat VariableString VariablePointer VariableDown Timer VariableUp Timer VariableInteger TableFloat TableString TableCommunication Handle

Chart



Advantages of Using PointersFor certain types of operations, pointers can speed up programming and make the strategy more efficient. Pointers are usually recommended only for experienced programmers, however, because their misuse can result in unpredictable behavior. They also complicate strategy debugging. If you use too many pointers, it’s easy to lose track of what’s pointing to what.

If you choose to use pointers, be sure you use the text tool to document your charts in detail.

Referencing Objects with PointersThere are two types of pointers—pointer variables and pointer tables.

Pointer Variables. A pointer variable contains a single pointer to a single object. You can set the initial value for a pointer variable when you configure it, or you can set it later by using the command Move to Pointer.

Once the initial value is set, you can reference it using any command you would use for that type of object. For example, if the pointer points to a string variable, you can use any command for the pointer that you would normally use for a string variable, such as Append String to String or Convert String to Float.

Pointer Tables. A pointer table contains a list of objects of different types, each of which can be pointed to. For example, the object at index 0 could be a chart, the object at index 1 a digital point, and the object at index 2 a string variable. An example of using a pointer table for indexing is shown on page 92.

When you create a pointer table, no initial values are set. You can use the Move to Pointer Table command to set individual values in the table.

A pointer table element cannot be directly referenced. It must be copied to a pointer variable first, using the command Move From Pointer Table Element. Once it is in the pointer variable, you can reference it as you would any object of that type. For example, if index 3 in a pointer table points to a counter input, use Move From Pointer Table Element to put the counter input address in a pointer variable. Then you can use any command for the pointer variable that you would normally use with a counter input, such as Start Counter or Clear Counter.

SIMULATION COMMANDS


Simulation CommandsThe following commands are used for simulation and program testing:

The Disable commands disconnect the strategy from the real-world device, so that it can be tested without affecting field devices. While the real-world devices are disabled (or if they don’t exist) the IVAL commands can be used for testing and simulation. For details on individual commands, see the PAC Control Command Reference or online Help.

Communication to All I/O Points Enabled? IVAL Set Analog Max ValueCommunication to All I/O Units Enabled? IVAL Set Analog Min ValueDisable Communication to All I/O Points IVAL Set Analog PointDisable Communication to All I/O Units IVAL Set CounterDisable Communication to I/O Unit IVAL Set I/O Unit from MOMO MasksDisable Communication to PID Loop IVAL Set Off-LatchDisable Communication to Point IVAL Set Off-PulseEnable Communication to All I/O Points IVAL Set On-LatchEnable Communication to All I/O Units IVAL Set On-PulseEnable Communication to I/O Unit IVAL Set TPO Percent

Enable Communication to Mistic PID Loop1 IVAL Set TPO PeriodEnable Communication to PID Loop IVAL Turn OffEnable Communication to Point IVAL Turn OnI/O Point Communication Enabled? PID Loop Communication Enabled?I/O Unit Communication Enabled?

1 PAC Control Professional only



String CommandsThe following commands are used with strings:

Using StringsNOTE: All numbers in this discussion of strings are decimal unless otherwise stated.

A PAC Control string is a sequence of characters that can be grouped together. Characteristics of strings include the following:

• Strings are always referred to by name (and, if in a table, by index).

• Each character is represented by one byte.

• Each character is represented by its ASCII code (0 to 255).

• A string containing no characters is referred to as an empty string.

• Strings are frequently used in serial communication as a container for moving numeric characters from one device to another.

• Although a string may appear to contain numeric values, it does not. Digits “0” through “9” are characters just as much as “A” through “Z”; they do not represent numeric values.

To illustrate, let’s look at the number 22. This is a decimal number representing a quantity of 22. The number 22 can be represented in a string in several ways; here are two of them:

Append Character to String Generate Forward CCITT on String

Append String to String Generate Forward CRC-16 on String

Compare Strings Generate Reverse CCITT on String

Convert Float to String Generate Reverse CRC-16 on String

Convert Hex String to Number Get Nth Character

Convert IEEE Hex String to Number Get String Length

Convert Integer 32 to IP Address String Get Substring

Convert IP Address String to Integer 32 Move from String Table Element

Convert Number to Formatted Hex String Move String

Convert Number to Hex String Move to String Table Element

Convert Number to String Move to String Table Elements

Convert Number to String Field Set Nth Character

Convert String to Float String Equal to String Table Element?

Convert String to Integer 32 String Equal?

Convert String to Integer 64 Test Equal Strings

Convert String to Lower Case Verify Checksum on String

Convert String to Upper Case Verify Forward CCITT on String

Find Character in String Verify Forward CRC-16 on String

Find Substring in String Verify Reverse CCITT on String

Generate Checksum on String Verify Reverse CRC-16 on String

STRING COMMANDS


– As “22”: two character 50’s (The ASCII code for 2 is 50.)

– As “16”: a character 49 (“1”) and a character 54 (“6”) (The hex value of 22 is 16.)

Note that the string representation of the number 22 is no longer a number. It is simply one or two ASCII characters. The string representation of a number must be converted to a numeric value if it is to be used in calculations. Several Convert commands are available for this purpose.

• In standard PAC Control commands, do not use double quotes around string literals. You can use single quotes, but they are not required.

• In OptoScript code, you must use double quotes for string literals. See “11: Using OptoScript,” for more information.

String Length and WidthThe width of a string is the maximum length a string can be; length is the actual number of characters contained in the string. A string with a width of 100 may currently be empty, which means its length is zero. A string with a width of 10 containing the characters “Hello ” has a length of six (five for “Hello” and one for the space after the “o”). Although a string’s length may change dynamically as the string is modified by the program, its width remains constant.

When you configure a string variable or string table, you set the width of the string. All the strings in a PAC Control string table must be of the same width.

PAC Control supports a maximum string width of 1024. For applications requiring wider strings, you can use several strings to hold the data, use string tables, or use numeric tables, as described in the next section.

Using Numeric Tables as an Alternative to StringsSince a string is nothing more than a sequence of characters, you can store a string in a numeric table, with each table element holding a character. The advantage of using numeric tables for strings is that a numeric table can store strings of any size. The disadvantages are:

• Memory usage is much greater.

• No string conversion functions are available for numeric tables. An intermediate temporary string would be required to use string commands for these tables.

Strings in PAC Control can have a width of up to 1024.

Strings and MultitaskingAlthough string commands are completed before the current task loses its time slice, it is important to note that a string that is constructed in more than one step may require more than one time slice to complete.



For example, if a string is being constructed in two steps (such as Move String “Hello” and Append String to String “ World”), after the first step a task switch could occur, and another chart looking at the resulting string might see “Hello” rather than “Hello World.”

If another chart is relying on a completed string, you can use a temporary string for building the string, and then move it to the final string. This idea is illustrated in the following example, where a string variable named MSG_String is built in two steps using a temporary string:1. Move the string literal “The pressure is “ to a temporary variable named sTemp.2. Append a string variable, sPressure, to sTemp. 3. With the complete string now built, move sTemp to MSG_String.

Adding Control Characters to a StringYou can input most control characters in a string by typing a backslash ( \ ) followed by the two-character hex value of the character. For example, to add an ACK (CTRL+F ) character, enter \06 as part of the string.

This technique works for all control characters except null (\00), carriage return (\0D), line feed (\0A), backspace (\08), and CTRL+Z (\1A). To add these characters to a string, you must use the Append Character command.

To input a single backslash in a string, type in a double backslash ( \\ ).

Sample String Variable• Declared Name: String_1

• Declared Width: 22

• Maximum Possible Width: 1024

• Bytes of Memory Required: Declared Width + 4 = 22 + 4 = 26

A string is referred to by its name. Initially the previous string is empty, giving it a length of zero. Later, during program execution, seven characters are added to String_1, increasing its length to seven:

String_1Length is 0

String_1 O P T O 2 2

Width is

Width is

Length is

STRING COMMANDS


Sample String Table• Declared Name: Promo_Messages

• Declared Width: 26

• Maximum Possible Width: 1024

• Declared Length (Number of indexes, or items, in table): 5

• Maximum Possible Length (Size): 1,000,000

• Bytes of Memory Required: (Declared Width + 4) x Declared Length = (26 + 4) x 5 = 150

A string table is a collection of strings. Each string is referred to by the name of the table it is in and the index where it can be found. The length of the table is the number of strings it can hold. Because string table indexes start with zero, indexes can range from zero to the table length minus one.

The width of each string in the table is the same. The length of each string can vary from zero to the configured width of the table.

String Data Extraction ExamplesTo extract various pieces of information from a string, use the command Find Substring in String. Consider the following example:

One way to get two separate pieces of information from this string is to get characters 0–3 and then get characters 5 and 6, as shown in the following examples.

Find Substring in String: Example 1

String_1 string variable Start At 0 integer literal

Number Of 4 integer literalMove To Sub_String1 string variable (width = 5)

Results in:

Index 0 O P T O 2 2 S N A P P A C S Y S T E M SIndex 1 I n n o v a t i v e I / OIndex 2 D e l i v e r s c o n t r o l ,Index 3 p r o g r a m m a b i l i t y , a n dIndex 4 e n t e r p r i s e c o n n e c t i v i t y !

0 1 2 3 4 5 6


0 1 2 3 4

Sub_String1 O P T O

Width is



Find Substring in String: Example 2

String_1 string variable Start At 5 integer literal

Number Of 2 integer literalMove To Sub_String2 string variable (width = 5)

Results in:

String Building ExampleStrings are assembled using commands Move String, Append Character to String, and Append String to String. Consider the following original string and the examples that follow:

Move String

From OPTO string literalTo String_1 string variable

Results in (note that Move String erased the previous contents of the string):

Append Character to String

From 32 integer literal (represents a space)To String_1 string variable

Results in (note the space character in position 4):

Append String to String

From 22 string literalTo String_1 string variable

0 1 2 3 4

Sub_String2 2 2

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21

String_1 S N A P P A C

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21

String_1 O P T O

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21

String_1 O P T O

Length is

Length is

STRING COMMANDS


Results in:

Append Character to String

From 13 integer literal (carriage return)To String_1 string variable

Results in:

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21


0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21

String_1 O P T O 2 2 ¶

Length is

Length is



Comparison to Visual Basic and CThe following table lists PAC Control string commands and their equivalents in Microsoft Visual Basic® and C. If you are using OptoScript, see “E: OptoScript Language Reference,” for additional comparisons.

PAC Control Command Visual Basic C

Append Character to String S$ = S$ + Chr$(MyChar%)i = strlen(str);

str[i] = MyChar;str[i + 1] = 0;

Append String to String S$ = S$ + “Hello” strcat(str, “Hello”);

Convert Hex String Number 1% = “&h” + S$ sscanf(str,“%x”,&iNum);

Convert Number to Formatted Hex String S$ = Hex$(1%) sprintf(str,“%x”,iNum);

Convert Number to String S$ = CStr(1%) sprintf(str,“%d”,iNum);sprintf(str,“%f”,fNum);

Convert String to Float F = CSng(S$) sscanf(str,“%f”,&fNum);fNum = atof(str);

Convert String to Integer 32 I% = Clnt(S$) sscanf(str,“%d”,&iNum);iNum = atoi(str);

Get Nth Character MyByte% = ASC(MID$(Str$,n%,1)) MyByte = str[n];

Get String Length MyLENGTH% = LEN(Str$) iLEN = strlen(str);

Get Substring SubStr$ = MID$(Str$,i,n) strncpy(subStr,&str[i],n);subStr[n] = ‘\0’;

Move String STR$ = “Hello” strcpy(strDest,“Hello”);

Test Equal Strings Equal% = (STR$ = “Hello”) i = strcmp(str1,“Hello”);

String Equal? if STR$ = “Hi” then... if(!strcmp(str1,“Hi”))

String Equal toString Table Element? if STR$(n%) = “Hi” then... if(!strcmp(str1[n],“Hi”))

STRING COMMANDS


Convert-to-String CommandsThe five convert-to-string commands are typically used when printing a number to a port. The ASCII table on the following page shows how various parameters affect the string as it is converted. Note the following:

• Some commands add leading spaces to achieve the specified length. These spaces are indicated with underscores ( _ ).

• Floats (if used) are automatically rounded to integers before conversion except when using the command Convert Number to Formatted Hex String.

Command Parameters

Convert-to-String Commands

Num

eric

val

ue

to b

e co

nver

ted

Num

ber o

f dig

its

right

of d

ecim

al p

oint

Leng

th

Con

vert

Num

ber t

o Fo

rmat

ted

Hex

Str

ing

(Len

gth

8 re

quire

d fo

r flo

ats)

Con

vert

Flo

at

to S

trin

g

Con

vert

Num

ber

to H

ex S

trin

g

Con

vert

Num

ber

to S

trin

g Fi

eld

Con

vert

Num

ber

to S

trin

g

Floa

ts

16.0 1 4 41800000 16.0 10 1.6e+01 1.6e+01

16.0 2 4 41800000 **** 10 1.6e+01 1.6e+01

-16.0 1 4 C1800000 **** FFFFFFF0 -1.6e+01 -1.6e+01

1.23 1 4 3F9D70A4 _1.2 1 1.23e+00 1.23e+00

12.3 1 4 4144CCCD 12.3 C 1.23e+01 1.23e+01

0.0 1 4 00000000 _0.0 0 0.0e+00 0.0e+00

Inte

gers

16 1 4 0010 16.0 10 _ _16 16

16 2 4 0010 **** 10 _ _16 16

-16 1 4 FFF0 **** FFFFFFF0 _-16 -16

0 1 4 0000 0.0 0 _ _ _0 0

1000 1 2 ** ** 3E8 1000 1000

**** Indicates an overflow. The whole-number portion of the resulting string is too long for its space.



ASCII TableThe following table shows ASCII characters with their decimal and hex values. For characters 0–31, equivalent control codes are also listed; for example, a carriage return (character 13) is equivalent to a CTRL+M (shown in the table as ^M).

Dec Hex CC Char Dec Hex Char Dec Hex Char Dec Hex Char

0 00 ^@ NUL 32 20 Space 64 40 @ 96 60 ‘i

1 01 Â SOH 33 21 ! 65 41 A 97 61 a

2 02 ^B STX 34 22 “ 66 42 B 98 62 b

3 03 ^C ETX 35 23 # 67 43 C 99 63 c

4 04 ^D EOT 36 24 $ 68 44 D 100 64 d

5 05 Ê ENQ 37 25 % 69 45 E 101 65 e

6 06 ^F ACK 38 26 & 70 46 F 102 66 f

7 07 ^G BEL 39 27 i’ 71 47 G 103 67 g

8 08 ^H BS 40 28 ( 72 48 H 104 68 h

9 09 Î HT 41 29 ) 73 49 I 105 69 i

10 0A ^J LF 42 2A * 74 4A J 106 6A j

11 0B ^K VT 43 2B + 75 4B K 107 6B k

12 0C ^L FF 44 2C , 76 4C L 108 6C l

13 0D ^M CR 45 2D - 77 4D M 109 6D m

14 0E ^N SO 46 2E . 78 4E N 110 6E n

15 0F Ô SI 47 2F / 79 4F O 111 6F o

16 10 ^P DLE 48 30 0 80 50 P 112 70 p

17 11 ^Q DC1 49 31 1 81 51 Q 113 71 q

18 12 ^R DC2 50 32 2 82 52 R 114 72 r

19 13 ^S DC3 51 33 3 83 53 S 115 73 s

20 14 ^T DC4 52 34 4 84 54 T 116 74 t

21 15 Û NAK 53 35 5 85 55 U 117 75 u

22 16 ^V SYN 54 36 6 86 56 V 118 76 v

23 17 ^W ETB 55 37 7 87 57 W 119 77 w

24 18 ^X CAN 56 38 8 88 58 X 120 78 x

25 19 ^Y EM 57 39 9 89 59 Y 121 79 y

26 1A ^Z SUB 58 3A : 90 5A Z 122 7A z

27 1B ^[ ESC 59 3B ; 91 5B [ 123 7B {

28 1C ^\ FS 60 3C < 92 5C \ 124 7C |

29 1D ^] GS 61 3D = 93 5D ] 125 7D }

30 1E ^^ RS 62 3E > 94 5E ^ 126 7E ~

31 1F ^_ US 63 3F ? 95 5F _ 127 7F DEL

TIME/DATE COMMANDS


Time/Date CommandsThe following commands refer to time, dates, and days:

These commands can be used for timing a process or for making sure things happen according to a set schedule. For example, you could use the command Get Seconds Since Midnight at the beginning of a process and again at the end of the process, and then subtract the two numbers to find out how long the process took.

You can set the time and date on the control engine by synchronizing it with the PC; in PAC Control Debug mode, choose this option while viewing the control engine (Control Engine > Inspect). You can also use these commands to set the time and date on the control engine.

Dates and Days Time

Copy Date to String (DD/MM/YYYY) Copy Time to String

Copy Date to String (MM/DD/YYYY) Get Hours

Get Day Get Minutes

Get Day of Week Get Seconds

Get Julian Day Get Seconds Since Midnight

Get Month Get System Time

Get Year Set Hours

Set Date Set Minutes

Set Day Set Seconds

Set Month Set Time

Set Year



Timing CommandsThe following commands are used for timers and delays in a strategy.

Delay CommandsDelay commands are used frequently in strategies to pause the logic. Here are two reasons to use Delay (mSec) or Delay (Sec):

• To allow time for the state of an input to change before it is checked again. For example, a delay could give an operator time to release a button before the state of the button is rechecked, or allow time for an alarm state to change before rechecking.

• To let a chart give up the remainder of its time slice, when its logic does not need to run constantly. For more information on using delays in this way, see 1776, Optimizing PAC Project System Performance.

Using TimersTimers are a special type of numeric variable. a PAC Control timer stores elapsed time in units of seconds with resolution of milliseconds. Down timers continuously count down to zero, and up timers continuously count up from zero. Timers can be paused and continued.

To create a timer in PAC Control, configure a numeric variable and select the type Up Timer or Down Timer. You can use any PAC Control command (for example, Move) that references a numeric variable to access a timer. You can view the current value of a timer at any time in PAC Control Debug mode.

Since the timer is independent from the control engine’s clock, over thousands of seconds, the timer and the control engine’s clock will not match. Timers do not place any additional load on the CPU.

Down Timer Operation

The Set Down Timer Preset Value command sets the time the down timer will start from, but does not start the timer. Use the Start Timer command to start the timer counting down to zero. (Since the default preset value for a down timer is zero, nothing will happen if you use the Start Timer command before setting a value.)

Timers Stop Timer

Continue Timer Timer Expired?

Down Timer Expired? Up Timer Target Time Reached?

Pause Timer

Set Down Timer Preset Value Delays

Set Up Timer Target Value Delay (mSec)

Start Timer Delay (Sec)

TIMING COMMANDS


Alternatively, you can use the Move command to set the time the down timer will start from. If you use Move, the down timer begins counting down immediately. If program execution speed is a priority, use the Move command and put an integer value rather than a float into the timer. This action eliminates the float-to-integer conversion time.

Note that if you use the Move command, any value you set using Set Down Timer Preset Value is overwritten, and subsequent Start Timer commands start the timer from the value last sent by the Move command.

To determine if the timer is finished, use the condition Down Timer Expired? This condition is true any time the down timer has a value of zero. Down Timer Expired? is much faster than using the condition Equal? to compare the timer to a value of zero.

The Stop Timer command forces the timer to stop and puts its value at zero. If you want to halt the timer and have it maintain its value at the time it was stopped, use the Pause Timer command instead. When you use Pause Timer, you can move the timer’s value at the time it was stopped to a variable. You can also use the Continue Timer command to resume the timer where it left off.

Up Timer Operation

The Set Up Timer Target Value command sets the time for the Up Timer Target Time Reached? condition. It does not start the timer, however, and the timer does not stop when it reaches the target value. You must start the up timer from zero by using the Start Timer command.

If you use the Move command to move a value to an up timer, the value you moved becomes the target value and the up timer starts timing immediately. (Note that the timer does not start from the value you moved; it always starts at zero.)

The up timer does not stop when it reaches the target value. To determine if the timer has reached its target value, use the condition Up Timer Target Time Reached? This condition tests the timer to see if it is greater than or equal to the target time.

The Stop Timer command forces the timer to stop and resets it to zero. If you want to halt the timer and have it maintain its value at the time it was stopped, use the Pause Timer command instead. After you use Pause Timer, you can then move the timer’s value at the time it was stopped to a variable. You can also use the Continue Timer command to resume the timer where it left off.


11: 11: Using OptoScriptChapter 11

11: Using OptoScript

IntroductionThis chapter shows you how to create and use OptoScript, an optional programming language that can simplify certain types of operations in PAC Control. Modeled after computer languages such as C and Pascal, OptoScript code gives you an alternative to using standard PAC Control commands.

In addition to the examples provided in this chapter, see the Control Basic Examples directory on your hard drive for a fully annotated example strategy. OptoScript information is also provided in form 1638, the SNAP PAC Learning Center User’s Guide.

You will find OptoScript easy to use if you already have computer programming experience. Beginning programmers may also want to try it for control operations involving extensive math calculations, string handling, or complex loops and conditions.

This chapter assumes that you have some programming experience. Experienced programmers may want to see “Notes to Experienced Programmers” on page 402.

In this ChapterAbout OptoScript ..................................................... 322When To Use OptoScript ....................................... 322OptoScript Functions and Commands ........... 331OptoScript Syntax..................................................... 332OptoScript Data Types and Variables............... 334OptoScript Expressions and Operators ........... 338OptoScript Control Structures............................. 342Using the OptoScript Editor................................. 346Troubleshooting “Unable To Find” Errors ....... 350Troubleshooting Syntax Errors............................ 350Debugging Strategies with OptoScript .......... 352

ABOUT OPTOSCRIPT


About OptoScriptOptoScript is a procedural type of computer language similar to Pascal, C, or BASIC. It can be used within any PAC Control strategy or subroutine to replace or supplement standard PAC Control commands. It does not add new functions, but offers an alternative method within PAC Control’s flowcharting environment to simplify some common programming tasks.

OptoScript code cannot be mixed with commands in action or condition blocks; it is used in its own hexagonal flowchart block.

The following figure shows an example of an OptoScript flowchart block and its contents:

When To Use OptoScriptYou’ll want to use OptoScript for some common programming tasks that can be more difficult to do using standard PAC Control commands than using a procedural language. Extensive math calculations or complex loops, for example, can be done with standard commands but take up a lot of space on a flowchart.

When you use OptoScript, however, be aware that it is not self-documenting. Make sure you frequently use comments to explain what the code does, so that when you come back to it a year later—or when someone who is not as familiar with the code or the strategy must change it—it can be easily interpreted.

OptoScript editor

OptoScript code

OptoScript block

CHAPTER 11: USING OPTOSCRIPT


This section shows examples of using OptoScript:

• for math expressions

• for string handling

• for complex loops

• for case statements

• for conditions

• for combining math expressions, loops, and conditions.

For Math ExpressionsOptoScript is especially useful for mathematical computations. Math expressions are simpler and easier, and many of them are built right into the language, instead of requiring commands such as Add or Multiply. OptoScript has no limitations on the number of parentheses you can use in math expressions.

Here’s an example of a mathematical expression in OptoScript:integer1 = (integer2 + 2) * (float1 / (float2 - 2) - 3);

To accomplish the same computation using standard PAC Control commands, you would need to create at least two intermediate variables and use five instructions, as shown below.

WHEN TO USE OPTOSCRIPT


As you can see, the OptoScript version of this math expression is not only simpler to create, but also easier to understand once created.



For String HandlingIf your strategy transmits and receives serial data, you will want to try using OptoScript code. In standard PAC Control, forming and parsing (decoding) serial data can take several blocks. In OptoScript, string handling can be easier.

The following figure shows a flowchart designed to send the string request, “What type of plane?” and parse the response, “F14,” into a classification (F) and a model number (14). Compare these blocks and instructions with the ones on the following page, done in OptoScript.

The OptoScript version of the String_Handler flowchart is more compact. The string request can be built more easily, and parsing the response takes up much less space. If you handle more complex serial data than in the String_Handler example, you will find OptoScript code even more useful.

Building a string using standard PAC Control can require several commands.

If substrings or individual characters within a string must be handled, a standard PAC Control block can become quite large.



In OptoScript code, several strings and variables can be combined to build the request in one line.

In OptoScript code, the commands used to parse the response take up less space, so they all can be seen at once.



For Complex LoopsStrategies that use complex loops—for example, to repeat an operation while a condition remains true—are easier to create and take up less space in a flowchart when done in OptoScript. While loops, repeat loops, and for loops are all available.

• While loops repeat a process while a test is true (the test comes at the beginning of the process).

• Repeat loops repeat a process until a test is false (the test comes at the end of the process). This kind of loop is guaranteed to execute at least once.

• For loops repeat a process for a specified number of times.

Below is an example of a while loop as it would appear in standard flowchart commands, contrasted with the way it could be handled in an OptoScript block.

In OptoScript, the loop is in a single block that contains one condensed instruction.

In standard PAC Control commands, the loop takes several blocks, each containing one or more instructions.



For Case StatementsCase or switch statements create multiple decision points. They can also be easier to do using OptoScript. Here is an example of a case statement:

Using OptoScript for case statements saves space in the flowchart and lets you see all the possible cases in one dialog box.

In OptoScript, the code is all in one block.

In standard PAC Control commands, the case statement requires several sets of condition and action blocks, each containing commands.



For ConditionsLike loops and case statements, conditions can be simpler when done in OptoScript code. If/then, if/then/else, and if/then/elseif statements can all be mixed and nested as needed. Here’s an example of a simple if/then/else statement as it could be done in standard PAC Control commands and in OptoScript:

OptoScript is even more useful for more complex conditions, such as the following:

In OptoScript, a single block contains the statement.

In standard PAC Control commands, even a simple if/then/else statement requires three blocks.

In OptoScript, all the condition and action blocks and their commands are consolidated into one block.



For Combining Expressions, Operators, and ConditionsThe real power of OptoScript can be seen in complex operations.

Generally speaking, the more complex the combination of math expressions, logical and comparison operators, loops, and conditions, the more convenient it is to use OptoScript code rather than standard blocks and commands.

This portion of a sprinkler control system uses standard PAC Control blocks and commands to control watering of grass and trees.

The OptoScript version of Grass/Trees Control handles theloops, conditions, and operatorseasily in a single block.



OptoScript Functions and CommandsSince functions in OptoScript are provided by commands almost identical to the standard commands in PAC Control, you have the same complete range of functions. There are no additional functions for OptoScript code, and you cannot make your own functions.

Standard and OptoScript CommandsIn many cases you can easily recognize OptoScript commands, because they are almost the same as standard PAC Control commands. All spaces are removed from the OptoScript commands, however, and in some cases words in the command are abbreviated or left out. Commands are case sensitive. Here are some examples of the same commands in PAC Control and in OptoScript:

Some commands are built into OptoScript functionality. Some of these have OptoScript commands and some do not; you can use either the built-in functionality or the OptoScript command, if it exists. Here are some examples:

See Appendix E for a table of all PAC Control commands and their OptoScript equivalents. In addition, OptoScript equivalents for each command are shown in the PAC Control Command Reference and in the online command help.

Using I/O in OptoScriptOne advantage of OptoScript is that any named I/O point can be used directly, wherever a numeric variable can be used, rather than requiring a variable. Digital points behave like

PAC Control Command OptoScript Command

Get Counter GetCounter

Set Down Timer Preset Value SetDownTimerPreset

Delay (mSec) DelayMsec

Convert Float to String FloatToString

Get Number of Characters Waiting GetNumCharsWaiting

PAC Control Command OptoScript Command Built-In Equivalent Example

Move = item1 = value

Add + 1 + 2

Less? < value1 < value2

Turn On TurnOn = [non-zero] digital3 = 1

Turn Off TurnOff = 0 digital3 = 0

Comment (Single Line) // // comment

Set Nth Character SetNthCharacter s1[5] = 'c'

OPTOSCRIPT SYNTAX


integer variables that have only two possible states: zero (off ) or non-zero (on). Analog points behave like float variables.

For example, you can turn a digital point off by simply assigning it a value of zero:Light_Switch = 0;

You can turn a digital point on by assigning it any value other than zero:Light_Switch = 1; Light_Switch = -1; Light_Switch = 486;

You can use I/O points directly in mathematical expressions:fLimit = Pressure_Input + 50;

Or use them directly in control structures, for example to turn off the light if the door is closed:if (not Door) then

Light_Switch = 0;endif

You can set an output based on the value of an input or a variable:LED01 = Switch_A;Proportional_Valve = fPressure_Control

You can use a point directly with a command:fRange = GetAnalogMaxValue(Temp_Input) - GetAnalogMinValue(Temp_Input);TurnOn(Fan_A);IsOn(Fan_A);

OptoScript Syntax Here is a sample section of OptoScript code to illustrate syntax. Indentation is not required, but is used for clarity.



NOTE: Each block has only one exit point. It is not possible to use return to jump out of the current block.

More About Syntax with CommandsAs noted in the previous sample, arguments for a command are listed in the parentheses following the command. Arguments are listed in order beginning with argument 1. To find out the arguments for any command, see the PAC Control Command Reference or online command help.

There are two types of OptoScript commands: procedure commands and function commands.

Procedure commands accomplish an action and return no value. Here are some examples:

fPressure = 300.0;

nTotal = ntTable[0] + ntTable[1] + ntTable[2];

while ((GetHours() >= 8) and (GetHours() < 17)) Fan_A = 1; wend

// Send alarm if oven temperature too hot.if (Oven_Temperature >= 450) then

Oven_Alarm = 1; // Set the oven alarm else Oven_Alarm = 0; // Clear the oven alarm endif

nCheck = GenerateChecksumOnString (0, sMessage);nError_Block = GetIdOfBlockCausingCurrentError();RemoveCurrentError();

sGreeting = “Hello, world!”;nPos = FindCharacterInString('!', 0, sGreeting);

Each statement is followed by a semicolon.

Table elements are put in square brackets next to the table name.

Parentheses are used as separators for expressions and operators. You can use an unlimited number of parentheses.

Line comments appear on a separate line or after a statement. They are preceded by two slashes and a space Block comments (not illustrated) are preceded by /* and followed by */.

Parameters (arguments) for a command are listed in order within parentheses following the command. Commands that have no arguments must still include the parentheses.

An individual character can be in single quotes or in double quotes, depending on its type. A string must be in double quotes.

SetDownTimerPresetValue (60.0, Minute_Timer)

command (argument 1, argument 2)

EnableIOUnitCausingCurrentError ()

command (no arguments)

OPTOSCRIPT DATA TYPES AND VARIABLES


RemoveCurrentError();ClampInt32TableElement(10, 0, 5, x1);

Function commands return a value from their action, so the value can be placed somewhere. In the following examples, the value is placed in the variable at the beginning of the statement:nMonth = GetMonth();fSquare_Root = SquareRoot(99);nPosition = FindCharacterInString('S', 0, sName);

When you compare these examples to the identical commands in standard PAC Control, you’ll notice that the returned value for the standard PAC Control command is an argument. In OptoScript the returned value is not an argument, thus reducing the number of arguments by one. In the first example, the standard command Get Month has one argument, which is where the result is placed. The OptoScript command equivalent, GetMonth, has no arguments and places the result in the variable.

In most cases you will use the value a function command returns by placing it in a variable, a control structure, or a mathematical expression. Occasionally, however, you may not need to use the result. For example, the command StartChart returns a status. If you do not need to track the status, you can ignore it by not placing the result anywhere, for example:StartChart(Fan_Control);

OptoScript Data Types and VariablesUnlike most procedural languages, PAC Control maintains a database of all declared variables, which is shared with PAC Display. Variables are not declared in OptoScript code, but are created (declared) within PAC Control. (See “9: Using Variables and Commands.”) Variables are not declared in OptoScript because local variables are not allowed. All variables are global for the strategy (or global within a subroutine).

If you use a variable in OptoScript code that does not currently exist in the strategy, you’ll receive an error message when you test compile the code and can add the variable then.

Variable Name ConventionsWith OptoScript and in PAC Control generally, it’s a good idea to get into the habit of indicating the variable type in each variable’s name. Some variable types may be obvious in the name itself, but others are not. For more information, see “Naming Conventions” on page 82.



Using Numeric LiteralsHere are examples of how to use numeric literals in OptoScript. Formats are automatically converted if they don’t match the variable type. For example, if a value of 300.2 were assigned to an integer 32, the value would be converted to 300.

Making Assignments to Numeric VariablesValues are easily assigned to variables.

Using StringsAs noted in the section on syntax, a string in OptoScript must be in double quotes. An individual character can be used either as a string (in double quotes) or as an integer value representing that character in ASCII (in single quotes). When you assign a single character to a string, use double quotes to avoid a syntax error:

sString = "a";

Decimal Integer 32 Literals assigned to variables:nVariable1 = 0;nVariable2 = 10;nVariable3 = -123;

Decimal Integer 64 Literals assigned to variables. Inte-ger 64s have an i64 at the end:dVariable1 = 0i64;dVariable2 = 10i64;dVariable3 = -123i64;

Hexadecimal Integer 32 Literals assigned to variables. Hex notation starts with 0x. Digits A–F may be upper or lower case:nVariable1 = 0x0;nVariable2 = 0x10;nVariable3 = 0x12AB34CD;nVariable3 = 0x12ab34cd;

Hexadecimal Integer 64 Literals assigned to variables:dVariable1 = 0x0i64;dVariable2 = 0x10i64;dVariable3 = 0x1234567890ABCDEFi64;

Float Literals assigned to variables (Float literals may use scientific notation):fVariable1 = 0.0;fVariable2 = 12.3;fVariable3 = -123.456;fVariable3 = -1.23456e2;fVariable3 = -12345.6e-2;

Simple Integer 32 assignments:n1 = 1;n2 = n1;

Simple Integer 64 assignments:nn1 = 2i64;nn2 = nn1;

Simple Float assignments:f1 = 3.0;f2 = f1

Simple assignments between different data types (Types will be automatically converted to match):n1 = 4.0;nn1 = n1;f1 = n1;

OPTOSCRIPT DATA TYPES AND VARIABLES


To change a single-character integer into a string, use the Chr() keyword as shown below:

NOTE: If you intend to retrieve the string data in either PAC Display or OptoOPCServer, to avoid an error do not use the Chr( ) keyword character to insert an embedded null, e.g. Chr(0).

Strings can be used in the following ways.

sString = Chr('a'); sString = Chr(97);

n = 97;sString = Chr(97)

String literals (must be all on one line):sGreeting = "Hello, world!"

String variables:sOutgoing = sIncoming;

When you use the Chr() keyword to assign a character value to a string variable, you can either quote a character or give its ASCII value. For example, the following two statements are equivalent

sString1 = Chr('A');sString1 = Chr(65);

A string can be thought of as a table of characters. The number in square brackets is the character’s index. (Note that the index starts with the number zero.) The following code would result in sGreeting equaling “Hello!!!”sGreeting = "Hello...";sGreeting[5] = '!';sGreeting[6] = '!';sGreeting[7] = sGreeting[6];

A character element of a string variable may be treated like an Integer 32 value:nNumber = sString2[1] * sString2[2];

Clear a string using empty quotation marks:sString1 = "";

The + operator is used to paste strings together. There is no limit to the number of + operators you can use on a line. The + operator must be used in an assignment statement:sString1 = "Hello ";sString2 = "world";sString3 = "!";After the three lines above, the following two lines would produce the same result:sString4 = sString1 + sString2 + sString3;sString4 = sString1 + "world" + sString3;

Use the += operator to append one string to another and change the value of one of them into the result. In the following example, the value of sName would change to “Smith, John”:sName = "Smith, ";sFirstName = "John";sName += sFirstName;

The Chr() keyword can be used to convert a numeric value into a one-element string:sString5 = sString1 + sString2 + Chr('!');sString5 = sString1 + sString2 + Chr(33);



Working with PointersPointers can be tricky, but they are powerful tools. For more information on using pointers, see “Pointer Commands” on page 306.

For the following examples, assume that:n1 = 5;f1 = 9.2;s1 = "test 123";

Set the pointer. The types must match or the control engine will generate an error.pn1 = null;pn1 = &n1;pf1 = &f1;ps1 = &s1;pcht1 = &Powerup;

To see if a pointer is pointing to something, use the compar-ison operator == (see page 339) to compare it to null. This use is similar to standard PAC Control condition commands such as Pointer Equal to NULL? For example: n2 = pn1 == null;n2 = null == pn1;if (pt1[0] == null) then

Use * to de-reference a pointer; it will then behave just like the variable to which it is point-ing. The following two statements are equivalent:n2 = *pn1 + *pf1n2 = n1 + f1;

To move a value from a pointer to another pointer:pVariable0 = &*pVariable1;

To move a value from a pointer to a pointer table:ptTable[0] = &*pVariable4;

Pointers are very useful when you don't know what variables need to be used until runtime. For instance, the next example uses a switch statement (see page 343) to determine which variable to use based on the day of the week. It then uses a pointer to perform a calculation using the correct variable.switch (GetDayOfWeek())

case 0: // Sundaypn1 = n2; break

case 6: // Saturdaypn1 = n3; break

default: // Monday-Fridaypn1 =5 n4; break

endswitch

Use the pointer to set the chosen variable.*pn1 = n5 * f1 - 5;

OPTOSCRIPT EXPRESSIONS AND OPERATORS


Working with TablesFollowing are some examples for using numeric, string, and pointer tables.

OptoScript Expressions and OperatorsOptoScript includes mathematical expressions as well as comparison, logical, and bitwise operators. Because expressions and operators are built into the OptoScript language, several standard PAC Control commands such as Multiply, Bit Shift, and Greater Than or Equal? are not used.

Numeric tables:ntTable1[0] = 1;ntTable1[1] = 2.0;ntTable1[2] = nVar1;ntTable1[3] = ntTable1[2];ntTable1[4] = ntTable1[ntTable1[0]];ntTable1[5] = nVar1 + ntTable1[2] * 3.1;nVar1 = ntTable1[0];nVar1 = (ntTable1[0] + ntTable1[1]) * ntTable1[2];

String tables:stStrT1[0] = "Hello, ";stStrT1[1] = "world";stStrT1[2] = stStrT1[0] + " " + stStrT1[1] + Chr('!');sString1 = stStrT1[2];

Pointer tables:ptTable6[0] = &*pVariable2;ptTable6[1] = nVar1;ptTable6[2] = stStrT1[0];stStrT1[0] = *ptTable6[2];

Pointer tables. Note that types are not checked when putting pointers into a pointer table. However, when a pointer is moved from a pointer table element into a pointer variable, the types are checked at runtime by the control engine and must match. For example, assume that the following elements have been placed in table ptPointT:ptPointT[0] = null;ptPointT[1] = &nLED_A;ptPointT[2] = &fTemp;ptPointT[3] = &sString1;ptPointT[4] = &Powerup;Based on this information, the first two of the following statements are good. The third one is bad and will cause a control engine error, because the element at ptPointT[3] is a string and therefore does not match the variable pntl, which is defined as an integer 32:pn1 = ptPointT[1];pf1 = ptPointT[2]; pn1 = ptPointT[3];



Using Mathematical Expressions

Using Comparison Operators

AdditionnCount = nLast_Count + 2;fPressure = 1.5 + fReading;nTotal = nMonday + nTuesday + 10;

SubtractionnNumber_A = nNumber_B - 250;fRange = fMax_Temp - fMin_Temp;

MultiplicationnQuantity = nBoxes * 12;nHours = nSeconds * 60 * 60;fMax_Speed = fSpeed * 16.52;

DivisionnBoxes = nCount / 6;fConversion = fLimit / 2.0;

Modulo division. If any argument is a float, it is rounded to an integer before the division occurs.nVar1 = nVar2 % 2;nVar1 = 2 % nVar2 % nVar3;fFloat1 = fFloat2 % 2.5;

Mixture of operators. nAvg = (nHrs_A + nHrs_B) / 2;nVar1 = fFloat2 + nVar3 * 4;

Use parentheses to clarify groupings and meaning. You can use an unlimited number of parentheses.nVar1 = nVar2 * (fFloat2 - 2.0);nVar1 = (nVar2 + 2) * (nVar3 + (fFloat1 / (fFloat2 - 2)) - 3);

The *, /, and % operators have greater precedence than + and -. (See page 406 for the order of precedence.) In the following lines, line #1 is equivalent to line #3, not to #2.n1 = n2 + n3 * n4; n1 = (n2 + n3) * n4; n1 = n2 + (n3 * n4);

All OptoScript comparison operators return an Integer 32 value of zero (false) or of non-zero (true). OptoScript supports the following comparison operators for comparing two numeric values:

Operator and Meaning Example

==<><<=>>=

equalnot equalless thanless than or equalgreater thangreater than or equal

nVar1 = nVar2 == fFloat3;nVar1 = nVar2 <> fFloat3;nVar1 = nVar2 < fFloat3;nVar1 = nVar2 <= fFloat3;nVar1 = nVar2 > fFloat3;nVar1 = nVar2 >= fFloat3;

More complex examples:nVar1 = (nVar2 * 2) == (fFloat3 / 9.5);nVar1 = (nVar2 * 2) < (fFloat3 / 9.5);

OPTOSCRIPT EXPRESSIONS AND OPERATORS


You can also use a comparison operator to test whether two strings are equal. For example:nVar1 = sString1 == sString2;nVar1 = sString1 == "abc";nVar1 = sString1 == stStrT1[0];nVar1 = stStrT1[0] == stStrT1[1];

When you use a comparison operator in an if statement, it isn’t necessary to put the result in a variable because the result is used (consumed) by the if:if (fICTD_Input <= Avg_Temp) then

Fan_A = 0;endif



Using Logical Operators

Using Bitwise Operators

All OptoScript logical operators return an Integer 32 value of zero (false) or of non-zero (true). OptoScript sup-ports the following logical operators for numeric values:

Operator and Meaning Example

andorxornot

Result is true if both values are trueResult is true if at least one value is trueResult is true if only one value is trueinvert the logical value

nVar1 = nVar2 and nVar3;nVar1 = nVar2 or nVar3;nVar1 = nVar2 xor nVar3;nVar1 = not nVar2;

Any number of logical operators can be chained together:nVar1 = nVar2 and nVar3 and nVar4;nVar1 = nVar2 and nVar3 or nVar4;

Logical operators are left-associative. For exam-ple, these two lines are equivalent:nVar1 = nVar2 and nVar3 ornVar4;nVar1 = (nVar2 and nVar3) ornVar4;

The not operator precedes a value (it only takes a value on its right-hand side):nVar1 = not nVar2;

The following two lines are equivalent:nVar1 = not nVar1 and not nVar2;nVar1 = (not nVar1) and (not nVar2);

Logical operators can be combined with comparison operators to create complex logical expressions:nVar1 = (nVar2 < 1) and (nVar3 == 6.5);nVar1 = (nVar2 < 1) and (sString1 == "abc");nVar1 = ((nVar2 < 1) and (nVar4 xor nVar5) or (not (fFloat1 == fFloat2));nVar1 = not (nVar2 < 5); // same as "nVar1 = nVar2 >= 5;"

When you use a logical operator in an if statement, it isn’t necessary to put the result in a variable because the result is used (consumed) by the if:if (Motor_1 or Motor_2) then

Motor_3 = 0;endif

All OptoScript bitwise operators operate on integer values. OptoScript supports the following bitwise operators:

bitandbitorbitxorbitnot<<>>

(bitwise and)(bitwise or)(bitwise xor)(bitwise not)(left shift)(right shift)

Use the bitwise and operator to and together the two values bit by bit:n1 = n2 bitand 2; n1 = n2 bitand n3;

Hex literals can be convenient:n1 = n2 bitand 0x0002;

OPTOSCRIPT CONTROL STRUCTURES


PrecedenceFor a list of operators from highest to lowest precedence, see “Operators” on page 406.

OptoScript Control StructuresOptoScript provides the following structures to control the flow of logic in the code:

• “If Statements” (below)

• “Switch or Case Statements” on page 343

• “While Loops” on page 344

• “Repeat Loops” on page 345

• “For Loops” on page 345

Use the bitwise or operator to or together the two values bit by bit:n1 = n2 bitor 2; n1 = n2 bitor 0x0002; n1 = n2 bitor n3;

Use the bitwise xor operator to xor together the two val-ues bit by bit:n1 = n2 bitxor 2; n1 = n2 bitxor 0x0002;n1 = n2 bitxor n3;

The left-shift operator shifts the left value's bits to the left by the right value:n1 = n2 << 2; // left shift n2's value by 2n1 = n2 << n3; // left shift n2's value by n3The right-shift operator shifts the left value's bits to the right by the right value:n1 = n2 >> 2; // right shift n2's value by 2n1 = n2 >> n3; // right shift n2's value by n3



If StatementsIf statements offer branching in logic: if statement A is true, then one action is taken; if statement A is false (or statement B is true), a different action is taken. If statements are very flexible; here are several examples of ways you can use them.

Switch or Case StatementsA switch or case statement also offers branching logic and can be used in place of if statements when the expression can match one of a number of numeric values. The value for each case can be a numeric constant or a mathematical expression only. Comparisons and logical operators cannot be used in cases, nor can strings. If a case involves a float, the float is converted to an integer before use. Notice that only one case can be tested at a time.

Any numeric value can be tested by the if statement (NOTE: The value is first converted to an Int32):if (n1) thenf1 = 2.0;

endif

Since a comparison operator returns an Integer 32 value, it can be used as the test value:if (n1 > 3) thenf1 = 2.0;f2 = 6.5;

endif

Complex logical operations can also be used: if ((n1 > 3) and (not n1 == 6)) thenf1 = 2.0;f2 = 6.5;

endif

An optional else statement can be added:

if (n1 > 3) thenf1 = 2.0;f2 = 6.5;

elsef3 = 8.8;

endif

Multiple elseif statements can be used to chain together sev-eral tests. The else statement is still allowed at the end.

if (n1 > 3) thenf1 = 2.0;f2 = 6.5;

elseif (n1 < -3) thenf3 = 8.8;

elseif (n1 == 0) thenf3 = f1 * f2;

elsef1 = 0;f2 = 0;f3 = 0;

endif

If statements can be nested. Each if requires an endif:

if (n1 > 3) thenf1 = 2.0;f2 = 6.5;

if (n1 % 10) thenf1 = f1 * 2;f2 = f2 * 3;

elsef3 = 0;

endifendif

OPTOSCRIPT CONTROL STRUCTURES


Here’s an example of a switch statement.

While LoopsThe while loop is used to execute a list of statements while a given condition is true. The condition is tested at the beginning of each loop.

For example, this loop sets the first five elements (elements 0 through 4) of a table (ntTable) to a value of 10:

While loops can be nested and can contain other kinds of program statements. Each while needs a matching wend at the end. For example:

switch (nNumber) case 1: f1 = 10; break case 2: f1 = 15; break case (n2 * 2): f1 = 20; break default: f1 = 0; f2 = -1; break endswitch

The value of the expression in parentheses, nNumber, is compared to each of the cases. If the case matches the value of nNumber, the action is taken.

If a case matches the value of nNumber, the break statement after citation immediately exits the switch. Notice that a semicolon is not used after break.

If no case matches, the default action is taken. Using a default is optional; if you use it, it must be at the end of the list.

A switch statement must be followed by endswitch.

You can use a mathematical expression as a case.

Make sure you use a colon (:) after each case.

nIndex = 0;while (nIndex < 5)

ntTable[nIndex] = 10; nIndex = nIndex + 1; wend

Initialize the counter.Execute loop if condtion is true.Set the table element.Increment the counter.

n1 = 0; while (n1 < 100) while ((n1 > 50) and (n1 < 60))

nt1[n1] = n1 * 100; n1 = n1 + 1; wend

nt1[n1] = n1; n1 = n1 + 1; wend



Repeat LoopsRepeat loops, in contrast to while loops, are used to execute a list of statements until a given condition is true. Because the condition is tested at the end of each loop, the content of the loop will always be executed at least once.

This example sets the first five elements of ntTable to 10. Compare this example to the example for while loops to see the difference.

Repeat loops can be nested and can contain other kinds of program statements. Each repeat statement needs a matching until statement at the end.

For LoopsFor loops can be used to execute a list of statements a certain number of times.

The for line sets up a predefined initial value and a predefined final value for the counter that counts the repetitions. The line also includes the steps by which the counter gets from its initial value to its final value (step 1 counts by ones; step 2 counts by twos, and so on). The step is required. The counter can be any numeric variable or I/O point, but its value will always be a whole number. The initial value, final value, and step can be any numeric expression; they are converted to integer 32s.

CAUTION: A step value of zero creates an infinite loop. A float step value between –0.5 and 0.5 also creates an infinite loop, since it is rounded to zero when converted to an integer 32.

This example results in nVariable equaling 6:

nIndex = 0; repeat ntTable[nIndex] = 10; nIndex = nIndex + 1; until (nIndex >= 5);

Initialize the counter.

Set the table element.Increment the counter.Execute loop if condtion is true.

nVariable = 1;for nCounter = 0 to 4 step 1nVariable = nVariable + 1;

next

The counter starts at zero, and its final value is 4. It will count up one step at a time.

The for loop must end with next.

USING THE OPTOSCRIPT EDITOR


For loops can be nested and can contain other types of statements. Each for requires a next at the end.

Using the OptoScript Editor1. To use the editor, create an OptoScript block in the flowchart where you want the code

to appear. (For more information on creating charts and blocks, see “8: Working with Flowcharts.”) Double-click the OptoScript block to open the editor.

The editor is similar to the editor for Microsoft Visual Basic®. You can resize the editor window as needed to see the code.

The for loop counter can be used in the loop. This example sets the first five elements of table ntTable to 10:

for nIndex = 0 to 4 step 1ntTable[nIndex] = 10;

next

Other step amounts can be used, including negative steps. Do not use a zero step, which creates an infi-nite loop. This example sets elements 0, 2, and 4 of ntTable to 20:for nIndex = 0 to 4 step 2ntTable[nIndex] = 20;

next

Predefined values can be a numeric expression, but they are evaluated only at the beginning of the loop. For instance, the following example will loop 0 to 15 because the upper limit of nSide*3 is evaluated only at the beginning of the loop, not each time through the loop:nSide = 5;for nLength = 0 to (nSide * 3) step 1 nSide = 1;

next

Column and line numbers

Toolbar

Type OptoScript code in this area.

See results of test compile in this area.



The following tools are provided in the Optoscript toolbar:

2. Begin typing OptoScript code in the top area.

You’ll notice that what you type is automatically color-coded to help you:

– Blue—operators and control structures

– Purple—values

– Green—comments

– Black—commands and names of variables, I/O points, charts, and other items

– Red—string literals.

If you want to see white-space marks to help line up code, click the Toggle Whitespace button in the toolbar. To hide the marks, click the button again.

3. To use a command, place your cursor in the OptoScript code where you want the command to appear. Click the Insert Actions or Conditions button in the toolbar.


Insert Action Command Find

Insert Conditions Command Replace

Insert Conditions Command Toggle Bookmark

Test Compile Clear All Bookmarks

Cut Next Bookmark

Copy Previous Bookmark

Paste Toggle Whitespace

Undo Increase Indent

Redo Decrease Indent

USING THE OPTOSCRIPT EDITOR


4. In the Select Instruction dialog box, select the command group from the left-hand column, and then select the command name from the right-hand column.

For information on any command, highlight it and click Command Help, or just double-click the command name.

NOTE: If you know the command name, you can just type it into the OptoScript code. Remember that OptoScript command names may be different from standard PAC Control commands. See “E: OptoScript Language Reference,” for more information.

5. To include information about the instruction in the OptoScript code, select “Include parameter helps.”

6. Click OK.

The command appears in the OptoScript code.

7. To use a variable, table, I/O unit or point, chart, counter, timer, or similar item, place your cursor where you want the item to appear in the code. If you know the item’s exact name, enter it and skip to step 8. If you’re not sure of the item’s name, click the Variables in the toolbar.



8. In the Select Variable dialog box, select the variable type from the left-hand column, and then select the variable name from the right-hand column.

The item appears in the code.

9. Use the TAB key on the keyboard as you type to indent lines as needed. To increase or decrease indentation for a line of code you’ve already typed, highlight the line and click the Increase Indent or Decrease Indent button in the toolbar.

10. Enter comments to document what the code does, so anyone who must debug or maintain the code can clearly see your intentions.

Comments appear in green. Line comments must be preceded by two slashes, for example:// This is a line comment.

Block comments must be preceded by one slash and an asterisk, and be followed by the same two elements in reverse. For example:/* This is a block comment that goes beyond one line. */

11. Use the Bookmark buttons in the toolbar as needed to set or clear temporary bookmarks within the code and to move between them.

Bookmarks mark lines of code so you can easily find them and jump from one bookmark to the next. Bookmarks remain only while the editor is open; they are not saved when the dialog box is closed.

12. When you have finished entering all the code for an OptoScript block, click the Test Compile button in the toolbar to compile the code for this block.

TROUBLESHOOTING “UNABLE TO FIND” ERRORS


The code is compiled, and the results appear in the bottom part of the OptoScript window:

NOTE: The next time the chart is compiled, all OptoScript code within the chart will be compiled again.

If errors are found, you can fix them now or later. Begin with the first one (the one on the lowest-numbered line), since later errors are often a result of earlier errors. To check a command, place the cursor anywhere in the command name and click the Command Help button. If you need to add variables or other items that don’t exist in the strategy, do so after step 12.

13. When you have finished with the code in this OptoScript block, click OK to save your work and close the editor.

You return to the flowchart.

Troubleshooting “Unable To Find” ErrorsSee also, “Troubleshooting Syntax Errors” below.

If you test compile an OptoScript block and receive “unable to find” errors, try the following suggestions.

For Commands

Check the exact spelling of the command, including upper and lower case. OptoScript commands are similar to standard PAC Control commands, but contain no spaces and some abbreviations.

Also check that the command is necessary in OptoScript. Some common commands, including comparison commands such as Less? and mathematical commands such as Add,

Results after code is compiled



are replaced with operators built into the OptoScript language. Check Appendix “E: OptoScript Language Reference,” for equivalent OptoScript commands.

The easiest way to make sure the command you enter is valid is to enter it by clicking one of the Insert Command buttons in the OptoScript Editor and choosing the command from the Select Instruction dialog box.

For Variables or Other Configured Items

Variables, I/O units and points, counters, and other configured items in your strategy—as well as charts—have usually been created before you use them in OptoScript code. Check their exact spelling, including underscores and upper and lower case, to make sure they are correct in the code. The easiest way to make sure spelling is correct is to enter the variable or other item by clicking the Insert Variable button in the OptoScript Editor and choosing the item from the drop-down lists.

If the item has not yet been configured or created, use the normal PAC Control methods to do so. For help, see the chapters in this guide on configuring I/O and using variables.

Troubleshooting Syntax ErrorsCheck for the following common syntax errors:

Missing Code

Check for obvious errors first. For example, make sure nothing essential has been left out of (or unnecessarily added to) a statement:

Check to make sure operators are used correctly. You may want to review “OptoScript Expressions and Operators” on page 338.

If you are using control structures such as loops or if statements, especially if they are nested, make sure all required elements are present. For example, every if must have a then and an endif. See “OptoScript Control Structures” on page 342 for more information.

Type Conflicts

Type conflicts are caused when different data types are incorrectly mixed. For example, you cannot assign an integer to a string. Make sure data types are correct. It is easier to keep track of data types if you use Hungarian notation when naming variables. See “Variable Name Conventions” on page 334 for help.

Sample Statement Should Be Missing Code

iTotal = x + y + ; iTotal = x + y + z; Last operator missing a variable

iTotal = x + y + z iTotal = x + y + z; Semicolon missing

sGreeting = Hello!" sGreeting = "Hello!" First quotation mark missing on the string

iTime = Get Hours; iTime = GetHours();Extra space in command name; parenthe-ses missing after the command

x = (1 + (x - y); x = (1 + (x - y)); Parentheses mismatched (last half missing)

DEBUGGING STRATEGIES WITH OPTOSCRIPT


Debugging Strategies with OptoScript Before trying to debug strategies containing OptoScript code, make sure the code has been compiled within each block, or choose Compile All to do all blocks at once.

When you begin debugging the strategy, start by stepping through whole blocks. If you run across a problem, then step within that block. Stepping within the block is discussed in “Choosing Debug Level” on page 185.


12: 12: Using SubroutinesChapter 12

12: Using Subroutines

IntroductionThis chapter shows you how to create and use subroutines.

In this ChapterAbout Subroutines................................................... 353Creating Subroutines .............................................. 355Using Subroutines.................................................... 361Viewing Subroutines............................................... 364Printing Subroutines ............................................... 365

About SubroutinesA subroutine is a custom command that represents a series of commands. Subroutines are useful anytime you have a group of commands that is repeated in a strategy or used in more than one strategy. Subroutines are built using the same tools and logic used to create charts. Once built, you can call them at any time from any chart in any strategy. (You cannot call a subroutine from another subroutine, however.)

Like charts, subroutines start at one block and proceed sequentially through command blocks to the end. They use variables, inputs, and outputs. They can use OptoScript code. Each subroutine is displayed in its own window, and you can open and view several subroutine windows at the same time.

Unlike charts, however, subroutines are independent from a strategy. You don’t need to have a strategy open to create or change a subroutine. And if you do have a strategy open, creating a subroutine has no effect on the open strategy unless you specifically link them together. (Debugging a subroutine, however, requires that it be called from a strategy.)

A second important difference between subroutines and charts is that subroutines offer two ways to work with variables and other logical elements: they can be passed in or they can be local to the subroutine.

ABOUT SUBROUTINES


• Passed-in items are passed into the subroutine by the strategy. They are referenced when the subroutine is executed. If a parameter is passed by reference, the subroutine will pass the value back to the strategy. For example, you could create a subroutine to add 3.0 to a passed-in float variable. If they are passed by value, the updated value is not passed back to the strategy by the subroutine. For more information, see the next section, “Data Types for Subroutines.”

When the subroutine ends, the float variable will contain a new value. Passed-in items are called subroutine parameters, and you can use up to 12 of them in a subroutine.

• Local items are created when a subroutine begins, and they are destroyed when it ends. For example, a subroutine could take a passed-in item, copy it to a local variable, and add 3.0 to that local variable for use within the subroutine. The local variable is created when the subroutine is called, and it disappears when the subroutine ends.

Data Types for SubroutinesThe following data types may be used in subroutines for both passed-in items and local items:

• Numeric variables (integers, floats, and timers)

• Numeric literals (integers and floats). Other types can be passed into the subroutine through literals, however; see below for more information.

• Numeric tables

• String variables

• String literals

• String tables

• Communication handles

The following data types are also supported:

• For passed-in items: I/O points, I/O units, and pointer tables

• For local items: pointer variables

The following data types are not supported in subroutines: PID loops and charts.

Although most variables passed in and out of a subroutine must be of a specific type, literals that are passed into subroutines can take several types. Using a string literal, you can pass in either a string literal or a string variable. Using a numeric literal, you can pass in an analog point, a digital point, an integer variable, a float variable, or a timer variable. If you are familiar with other programming languages, literals are similar to “passed by value” parameters, while variables are like “passed by reference” parameters.

This flexibility in using literals makes it easier to use a subroutine in multiple strategies. For example, a literal passed into a subroutine from two strategies might be a float value in one strategy and an analog point in the other.

CHAPTER 12: USING SUBROUTINES


Creating Subroutines

Tips for SubroutinesAs a general rule, keep subroutines as small as possible to do the job they’re intended for. Extra variables and unnecessarily large table sizes can affect the memory available for running subroutines.

A Put Status In parameter appears automatically in every subroutine. This parameter is used to let you know whether the subroutine was called successfully, in the same way that function commands return a status. Make sure that you always check the status code after calling a subroutine. Subroutine status codes are:

Drawing the Flowchart1. In the PAC Control main window (with or without a strategy open), choose Subroutine

> New.

The Create New Subroutine dialog box appears.

2. Enter a subroutine name.

The subroutine name will become a command (instruction) in PAC Control. It’s a good idea to make it a descriptive name indicating the purpose of the subroutine, for example, “Variable Increase Notification.” You cannot use the name of any existing command (for example, “Add”).

0 Success

-67 Out of memory

-69 Null object error. Make sure you are not passing a pointer that points to null.

-73Invalid subroutine or parameters. In configure mode, choose Edit > Find, select Global and Operand, and then click Find to search for objects with the same name as the subroutine. Rename any objects that you find.

CREATING SUBROUTINES


3. Navigate to the directory where you want to store the subroutine and click Open.

Unlike strategies, multiple subroutines can be saved to the same directory.

A new subroutine window is created.

4. Add blocks and connections and name the blocks as you would in a chart, as shown in the example below.

You can also copy existing flowchart blocks from another subroutine or chart and paste them into the new subroutine. See “Cutting, Copying, and Pasting Elements” on page 222.

5. Save the subroutine by selecting Subroutine > Save.



Configuring Subroutine ParametersBefore you can call a subroutine from a strategy, you must configure the variables and other logical items that are passed into it. These passed-in items, called subroutine parameters, are the only information that is shared between a subroutine and the calling strategy. Twelve parameters can be passed into a subroutine, and since a table can be a parameter, those 12 parameters can include a large amount of data.

An item passed into a subroutine may be called by one name in the strategy and by another name in the subroutine. In fact, if a subroutine is used for more than one strategy, it is good practice to select generic names in the subroutine. For example, if you create a subroutine to average values in any float table, the table might be named Float_Table in the subroutine. You could use this subroutine to average pressures in a table named Pressure_Values from a strategy, and Pressure_Values would be referred to as Float_Table in the subroutine. 1. With the subroutine open, select Subroutine > Configure Parameters.

The Configure Subroutine Parameters dialog box appears.

In this dialog box you determine the way the subroutine is called from the strategy.

2. From the Group drop-down list, choose the command group you want the subroutine to appear in.

For example, if you create a subroutine to find the average value of several variables, you could choose Mathematical as the command group. The default group is Subroutines.

3. (Optional) Enter a comment to explain the purpose of the subroutine.4. Notice that one parameter, Put Status In, has been automatically entered for you.



This parameter is used to return status information on the subroutine, and it always appears at the bottom of the parameter list. A subroutine essentially becomes a command within a chart; subroutines are similar to function commands that return a status. Since the system itself returns this status parameter, the name of the status parameter is not available in the subroutine. When you add the subroutine to a strategy, you choose the variable the status will be placed in.

IMPORTANT: Make sure you always check returned status codes for all subroutines. Subroutine status codes and their meanings are:

5. For each parameter you add, do the following steps.

NOTE: What you enter here appears in the Add Instruction dialog box when the subroutine is called from within the strategy. See page 359 for an example.

a. Highlight the first empty line (below the Put Status In parameter) and click Add to open the Add Subroutine Parameter dialog box.

b. In the Prompt field, enter the prompt text you want to show in the Add Instruction dialog box in the strategy. This field is limited to 16 characters.

c. In the Name field, enter the name of the parameter (the argument) as it will be referred to in the subroutine. This name is used within the subroutine only.

d. From the Type drop-down list, choose the type of item to be passed into the subroutine.Use variables for values the subroutine changes (passed by reference); use literals for values the subroutine uses but does not change (read-only or passed by value).

0 Success

-67 Out of memory

-69 Null object error. Make sure you are not passing a pointer that points to null.

-72 Nesting too deep (future use)



e. Click OK. The parameter appears in the Configure Subroutine Parameters dialog box, above the Put Status In parameter.

6. Repeat step 5 for each parameter. To change a parameter, highlight it and click Modify. To change the order of a parameter in the list, highlight it and click the up- or down-arrow button in the dialog box. To delete a parameter, highlight it and click Delete.

NOTE: You cannot delete the Put Status In parameter or change its order in the list, and you cannot delete a parameter that has a reference count greater than zero (indicating that it is used in the subroutine). Also, if you add or delete parameters after including a subroutine in a strategy, you may receive an error and will need to add the subroutine to the strategy again.

7. When the parameters appear the way you want them in the list, click OK.

The parameters you have named can now be used in the subroutine’s commands.

Configured Parameters Example

Here’s an example of a completed Configure Subroutine Parameters dialog box, showing three parameters to be passed into the subroutine. When the subroutine is called from the strategy, these parameters appear in the Add Instruction dialog box:

Up- and down-arrow buttons

Reference count



Adding Commands and Local VariablesAdding commands (instructions) to subroutines is exactly like adding instructions to charts. For help, see “Adding Commands” on page 247. If you are using OptoScript code within a subroutine, see Chapter 11 for help on creating code. You can copy and paste instructions from one block to another within the same subroutine; if you have trouble copying and pasting instructions from one chart or subroutine into another, simply paste the entire block and then modify it.

You may also need to add local items to be used in the subroutine only and discarded when the subroutine is finished. Adding variables to subroutines is also like adding variables to charts. For help, see “Adding Variables” on page 233.

Remember that the subroutine is separate from any strategy and can be called by any strategy. I/O units and points are specific to a strategy, so they cannot be added to a subroutine. Also, note that commands and OptoScript code within a subroutine can use only the passed-in and local items in the subroutine, not items in the strategy that calls the subroutine.

Subroutine file name

Names used in the subroutine may differ from those used in the strategy.

Add/Edit Instruction dialog box in the strategy

Prompt and Type parameters from the subroutine define the instruction in the strategy.



Compiling and Saving the Subroutine1. With the subroutine open, select Compile > Compile Subroutine.

When the subroutine has finished compiling, the cursor returns to its normal form.

2. Select Subroutine > Save.

Using SubroutinesTo use a subroutine in a strategy, you include it in the strategy and then add it as a command (instruction) so it can be called from a chart.

Including a Subroutine in a StrategySince subroutines are independent of strategies, you must include the subroutine in the strategy before you can use it.1. With the strategy open in Configure mode, double-click the Subroutines Included

folder on the Strategy Tree or select Configure > Subroutine Included.

The Subroutine Files dialog box appears, listing all subroutines currently included in the strategy. The example below shows no subroutines currently included.

2. Click Add.

USING SUBROUTINES


3. Navigate to the directory containing the subroutine you want to add and double-click the subroutine.

4. When the full path to the subroutine appears in the Subroutine Files dialog box, click OK.

The new subroutine appears in the Strategy Tree in the Subroutines Included folder.

Adding a Subroutine InstructionYou use a subroutine just like a PAC Control command: by adding the subroutine instruction to a block in the chart.

NOTE: Subroutines are located in the Subroutine group by default. If you want subroutines in a different group, you must change the group when you configure the subroutine's parameters. See “Configuring Subroutine Parameters” on page 357.

1. With the strategy open in Configure mode, open the chart that will use the subroutine.2. Double-click the block that will call the subroutine.

If it is an OptoScript block, list parameters (arguments) in order within parentheses, the same way you enter parameters for PAC Control commands (see “OptoScript Syntax” on page 332). Be sure to use the subroutine's OptoScript name, using underscores



instead of spaces. The Put Status In return value can be consumed by a variable (as shown below) such as a mathematical expression or a control structure.

nStatus = Variable_Increase_Notification( bCondition, nValue, Output1 );

For more information on entering a command (instruction) in OptoScript, see “Using the OptoScript Editor” on page 346.

3. In the Instructions dialog box, click where you want the instruction to be placed, and then click Add.

The Add Instruction dialog box appears.

4. In the highlighted Instruction field, enter the subroutine name (or choose it using the drop-down list, or click the Select button and locate it in the command group you chose).

NOTE: If you click Select, you will find subroutines located in the Subroutine group by default. If you want subroutines in a different group, you can change group when configure the Subroutine's parameters. See “Configuring Subroutine Parameters” on page 357.

The subroutine command appears in the dialog box, just as any command would, and the prompts you entered when you configured the parameters appear also.

VIEWING SUBROUTINES


5. Choose the Type and Name for each prompt from the drop-down lists.

You can configure variables on the fly as you would with any command. Remember that the Type was chosen when the parameters for the command were configured, so your Type choices may be limited.

6. When the Add Instruction dialog box is completed, click OK.7. Click Close to close the Instructions dialog box and return to the chart.

The chart is now set up to call the subroutine.

Debugging SubroutinesDebugging a subroutine is just like debugging a flowchart. When you are debugging a strategy that calls the subroutine, make sure the debug level is Full Debug (see page 185). Then use the Step Into button to step inside the block that calls the subroutine. The subroutine window automatically opens, and you can continue to step through blocks or lines inside the subroutine. As you step through blocks, subroutines, and charts, the tabs at the bottom of the window let you know where you are (see “Using Tabs to View Open Windows” on page 61).

You can also set breakpoints on any subroutine block as needed. See “Setting and Removing Breakpoints” on page 190 for more information.

Viewing SubroutinesSince subroutines appear on the Strategy Tree, it is easy to view information about them. A subroutine appears in two places on the Strategy Tree: in the Subroutines Included folder and in the folder for the chart that calls it.

Prompts



You can view, add, and change variables in a subroutine from the Strategy Tree, just as you would for a chart.

Viewing All Subroutines in a StrategyTo see all the subroutines in a strategy, double-click the Subroutines Included folder on the Strategy Tree. All subroutines associated with the strategy are listed in the Subroutine Files dialog box. Click and drag the right side of the box to see all the information. The path, filename, and reference count (how many times the strategy refers to the subroutine) are shown for each subroutine.

Printing SubroutinesFor steps to print a subroutine’s graphics, see “Printing Chart or Subroutine Graphics” on page 194. To view and print instructions in the subroutine’s blocks, see “Viewing and Printing Strategy or Subroutine Elements” on page 198.

In the Subroutines Included folder

In the calling chart folder

PRINTING SUBROUTINES



A: A: TroubleshootingAppendix A

A: Troubleshooting

This appendix provides general tips for resolving problems you may encounter while running PAC Control or communicating with your hardware. If you encounter problems with permissions in Windows, see page 376.

For information about types of errors and lists of error codes, see “B: Errors and Messages.”

Also check troubleshooting information in your controller’s user guide. See also, Opto 22 form 1690, the SNAP PAC Brain User's Guideform 1.

How to Begin TroubleshootingYou’ve built your strategy, but now you get errors when you try to download it, or it won’t run properly. How do you begin to figure out what’s wrong? The problem may be in communication with the control engine, in communication between the control engine and I/O, in a command, or in the strategy logic. Following are some steps to help you discover the cause.

1. Read Any Error Message BoxIf an error message box appears on the computer running PAC Control, it’s probably a PAC Control error. Here’s an example of a PAC Control error message:

STRATEGY PROBLEMS


2. Check Communication with the Control EngineIf there is no error message box, or the error indicates that there may be a communication problem, check whether the PC running PAC Control is communicating with the control engine. See “Checking Communication with the Control Engine” on page 370.

3. Check the Message QueueIf communication with the control engine is OK, check the message queue. To open the queue, see “Inspecting Control Engines and the Queue” on page 109. In the “List of Common Messages” on page 382, look up any errors you find in the queue. Errors are listed in numerical order. Queue errors may indicate problems with a command or with communication to I/O. Check the possible causes for help in fixing problems.

• For help with a command, look up details about the command in the PAC Control Command Reference or online help.

• For help with communication to I/O, see “Resolving Communication Problems” on page 371. Many of these suggestions apply to I/O as well as to control engines.

4. Check Status Codes in Your StrategyIf all is well up to this point, double-check Status Codes in your strategy. Status Codes are responses to a command that appear in a variable within your PAC Control strategy or as returned values in OptoScript. Your strategy should routinely check status codes and adjust logic as necessary to respond.

Status codes may indicate problems with a command or communication to I/O, or they may indicate a problem in the strategy logic. See “List of Common Messages” on page 382 for more information. Again, look at the possible causes for help in fixing problems.

5. Call Product SupportIf you cannot find the help you need in this book, the PAC Control Command Reference, or the SNAP PAC Brains User’s Guide, call Opto 22 Product Support. See “Product Support” on page 5 for contact information.

Strategy Problems

If You Cannot Delete an ItemSometimes when you try to delete an item in a strategy—a variable, a chart, an I/O unit or point—you receive a message saying “You cannot delete an item with a reference count

APPENDIX A: TROUBLESHOOTING


greater than zero.” This message means you cannot delete the item because other elements in the strategy use it.

You can use Find to locate all references to the item you want to delete. For help in using Find, see “Searching” on page 203.

Sometimes the reference counts can become incorrect due to cutting and pasting variables or importing charts into a strategy. If a reference count appears to be incorrect, you can rebuild the strategy database by following these steps:1. Click in the Strategy Tree to make it the active window.2. Press CTRL+R.3. Choose Compile > Compile All.4. Choose File > Save All.

The strategy database is rebuilt and the reference counts should be correct.

If You Have Memory ProblemsControl engine memory is allocated as shown in the following table. You can see the total amount of RAM and the amount of battery-backed RAM available for use by inspecting the control engine in Debug mode (see page 109).

In general, if you experience memory problems, you can reduce the amount of memory needed by checking strings and tables for lengths and widths that are longer than necessary.

If you are using subroutines, use the minimum number of variables and size of tables that the process requires. Also, less memory is used if only one chart in the strategy calls subroutines than if multiple charts call subroutines.

Since the battery-backed RAM contains variables initialized on download, if you have a large number of these on a smaller controller, you can run out of persistent RAM. To avoid this problem, use as few persistent variables as possible and initialize all other variables on strategy run.

SNAP-PAC-S1 SNAP PAC R-series

Total memory (RAM) 32 MB 16 MB

Memory used for control 32 MB 10 MB

Memory available for strategy and variables 16 MB 5 MB

Total battery-backed RAM 8 MB 2 MB

Battery-backed RAM for control* 8 MB 1 MB

* Stores persistent variables, variables initialized on download, autorun flag, and strategy archive. Note that strategies are not automatically saved in battery-backed RAM. Save your strategy to flash memory so it will be available if power is lost to the control engine. See “Saving a Strategy to Flash” on page 173.

CHECKING COMMUNICATION WITH THE CONTROL ENGINE


Although you can archive the strategy, the currently running strategy is not stored in battery-backed RAM. To make sure the strategy will run after a power loss, save the strategy to flash memory after downloading it. See page 173 for information on saving to flash.

Archiving Strategies to Battery-Backed RAM

Strategies are archived to battery-backed RAM, which is limited to 256KB. In addition to an archived strategy, battery-backed RAM holds persistent variables and variables that are initiated on download. If you have an unusually large strategy or large numbers of persistent variables or variables that are initialized on download, you may not have sufficient space for an archived strategy. See page 174 for more information on archiving.

Do You Use Online Mode?

If you frequently use Online mode to change your strategy, you may find you are having memory problems. When you change a chart in Online mode, a new copy of that chart is downloaded to the control engine, but the old one is not deleted. After you have made a few online changes, these additional chart copies begin to take up memory.

To avoid memory problems, stop the strategy after making several online changes. Completely compile and download the strategy, and old chart copies will be cleared from memory.

Checking Communication with the Control EngineYou can test communication with the control engine by using the PAC Terminal utility. 1. From the Start menu, choose Programs > Opto 22 > PAC Project 9.0 > Tools > PAC

Terminal.

The PAC Terminal window appears, showing all control engines configured on your system:



2. If no control engine is listed, configure one by choosing Configure > Control Engine and following directions on the screen. See “Configuring Control Engines” on page 97 for help.

3. To verify that a control engine in the list is communicating, double-click the control engine’s name.

The Comm. Loop Time (communication time) in the Inspect Control Engine dialog box indicates how long it takes to gather the information in the dialog box and is a good relative indicator of communication time.

This dialog box also shows the status of the current strategy and any errors in communication with the control engine. For further explanation, see “Inspecting Control Engines and the Queue” on page 109.

4. If you receive an error indicating a communication problem, go on to the next section.

Resolving Communication Problems

Matching PAC Control Configuration to the Real WorldI/O unit and point configuration in PAC Control must match actual I/O units and points with which the control engine is communicating. See brain and I/O module data sheets for specifications and information.

RESOLVING COMMUNICATION PROBLEMS


Resolving TCP/IP Cannot Connect Errors (-412)Many problems with Ethernet connections return a TCP/IP Cannot Connect error. Cannot connect errors are probably the most common communication problem with control engines. They indicate that a TCP/IP connection could not be made to the control engine within the specified time interval.

If you receive this error, first check the following:

• Make sure the control engine has been turned on.

• Verify that the correct IP address appears for the control engine.

• Make sure your control engine has been assigned a valid IP address. These controllers and brains come from the factory with a default IP address of 0.0.0.0, which is invalid. For help in assigning an IP address, see the PAC Manager User’s Guide.

• Make sure you have up-to-date drivers installed on your computer’s Network Interface Card (NIC). Contact your system administrator or the manufacturer of the card for help.

• If problems persist, you can increase the length of time before a timeout occurs. Choose Configure > Control Engines and change the Timeout (mSec) field to a larger number.

Pinging the Control Engine

If you still cannot communicate with the control engine after you have checked these items, try to reach it using the PING protocol.

Choose Start > Programs > MS-DOS Prompt. At the prompt, type: ping [control engine’s IP address]

(For example, type ping 10.192.54.40.)

If data is returned from the control engine, it can be found on the network.

If the PING command cannot be found—Verify that the PC has TCP/IP bound to and configured on the network adapter.

If you are running Windows 95 or Windows 98, follow these steps:1. Choose Start > Settings > Control Panel and double-click Network. 2. Highlight the adapter in the list. Make sure both NetBEUI and TCP/IP appear just below

the name of the adapter. Click Properties. 3. Highlight TCP/IP and click Properties. Verify that the IP address and subnet mask are

appropriate for your network.

If you are running Windows NT, follow these steps:1. Choose Start > Settings > Control Panel and double-click Network. 2. Click the Protocols tab. Make sure both NetBEUI and TCP/IP are listed. Highlight TCP/IP

and click Properties.3. Highlight the adapter name in the list. Verify that the IP address and subnet mask are




If you are running Windows 2000, follow these steps:1. Choose Start > Settings > Control Panel and double-click Network and Dialup

Connections. 2. Right-click your network card and choose Properties from the pop-up menu. Make

sure that TCP/IP is present and checked. 3. Highlight TCP/IP and click Properties. Verify that the IP address and subnet mask are


If you see the message “Destination host route not defined,” the control engine probably has an IP address and subnet mask that are incompatible with those on the computer. Subnetwork numbers and netmasks must be identical on the control engine and the computer.

If you see the message “No response from host,” check the following:

• Are the computer and control engine correctly connected? Is the control engine turned on?

• Are the IP address and subnet mask on the control engine compatible with those on the computer?

If your host computer has more than one Ethernet card, check your route table to make sure packets are routed to the correct adapter card.

If all else fails, connect the PC and the control engine using an Ethernet crossover cable, and retest the connection.

If you still cannot ping the control engine, contact Product Support. (See page 5.)

Other Troubleshooting Tools

Checking Detailed Communication Information Using PAC Message ViewerFor detailed information about each communication transaction, use the PAC Message Viewer utility.1. In the Start menu, choose Programs > Opto 22 > PAC Project 9.0 > Tools > PAC

MessageViewer.

You can also start PAC Message Viewer from PAC Terminal by choosing Tools > Start PAC Message Viewer, or from PAC Control in Debug mode by choosing Debug > Sniff Communication.

The PAC Message Viewer window appears.

OTHER TROUBLESHOOTING TOOLS


In most cases the main window is blank, indicating that no messages are being monitored between the PC and the active control engine. In some cases, for example when PAC Control launches PAC Message Viewer, messages should appear immediately.

2. To start monitoring or change the level of monitoring, choose View > Monitor Levels.

The Monitor Levels dialog box lists all the possible levels to monitor. You can click Refresh to make sure the list is up to date.

3. Highlight one or more of the monitor levels in the list, and click Close.

You return to the PAC Message Viewer window, where the changes you made are reflected at once. To stop monitoring, click Pause. To start monitoring again, click Resume. To erase all messages from the window, click Clear.

By default, communication messages in PAC Message Viewer are automatically saved to a log file named IOSNIF.LOG. You can toggle saving on and off by choosing File > Log to File.

Also by default, messages are temporarily stored in system cache memory before being saved to the log file. If you are having trouble with system crashes and need to capture messages just before a crash, however, you can choose File > Flush File Always to send messages directly to the log file.

4. To view or edit the log file, choose File > Edit Log File.

The file opens in a text editor. Logging is turned off when you open the file.

5. View or edit the file as needed, and then close it.



You return to the PAC Message Viewer window.

6. To resume logging, choose File > Log to File.7. To rename the log file or change its location, choose File > Select Log File. Navigate to

the location where you want to save the file and enter a name. Click OK.8. When you have finished monitoring communication, close the PAC Message Viewer

window.

If you leave it open, it will normally appear on top of other running programs. If you don’t want it to appear on top of other programs, choose View > Always on Top to toggle that option.

Checking File Versions for Opto 22 SoftwareSometimes problems may be caused by older or misplaced files. Product Support may ask you to run OptoVersion to check the versions and paths of your Opto 22 .dll and .exe files. Here’s how:1. From the Start menu, choose Programs > Opto 22 > PAC Project 9.0 > Tools >

OptoVersion.

2. In the OptoVersion window, click Find.

The utility searches your hard drive and prints a list of Opto-related files found.

3. To see more information on any file, double-click its name. To sort the list in a different order, click any column heading.

4. To email the information to Opto 22 Product Support, click E-mail.

The utility saves the list to a file named Version.bd in the same directory that contains OptoVersion.exe. If you use Microsoft Outlook as your email program, a new message automatically appears addressed to Product Support, with the version file attached.

5. If you use Microsoft Outlook, add comments to the new message and click Send.



6. If you use another email program, attach the Version.bd file to an email message and address the message to [email protected], along with an explanation of the problem you’re experiencing.

7. To save the file, click Save As. Give the file a name and save it in the location you want.

OptoVersion also creates a tab-delimited file with the same file extension and in the same directory. This file has the same name you gave it but with _Delimited added. For example, if you name the saved file Opto_software.txt, the tab-delimited file is named Opto_software_Delimited.txt. This file can be opened in Microsoft Excel or other programs to easily sort and view its contents.

Problems with Permissions in WindowsWhen you set up controllers on a computer running the Microsoft Windows operating system, typically you are using the computer with top-level “administrator” privileges. If someone later uses this same computer to run PAC Control or PAC Display, but logs in to the computer with lower-level, non-administrator privileges, the application may not recognize control engines that have been previously configured.

If this problem occurs, you can modify the permissions to let specific users access previously configured control engines without having administrator access. This is done using the Registry Editor utility. Follow the steps below.

WARNING: Use the Windows Registry Editor carefully. It is strongly recommended that you make a backup copy of your Windows Registry before continuing with this procedure. Without a backup copy, if you delete the wrong properties and cannot return the Registry to its original state, application and system files can become unusable and will have to be reinstalled.

1. From the Windows Start menu, select Run.

The Run dialog box appears.

2. Enter the following command in the Open field and press ENTER:

regedt32

NOTE: This is NOT regedit.exe, which is a similar tool.

The Registry Editor main window appears with several open windows inside it.

3. Select the HKEY_LOCAL_MACHINE window to make it active.4. Double-click the Software folder in the HKEY_LOCAL_MACHINE window.5. Select the Opto22 folder.6. In the Security menu, choose Permissions.

The Registry Key Permissions dialog box opens. Make sure that “Opto22” appears next to Registry Key at the top of the window.

7. Click Add.



8. In the Select Users, Computers, or Groups dialog box, select the name of the appropriate group or domain from the Look In drop-down list.

9. In the Name list, select the name of the user or group that should have control engine access and then click Add.

10. If it is not already selected, check “Full Control” in the Permission area. Make sure “Allow inheritable permissions from parent to propagate to this object” is checked.

11. Click OK.12. Select Registry > Exit to close the Registry Editor.13. Restart the computer.

The user or group you added can now use control engines without having administrator access.


B B: Errors and MessagesAppendix B

B: Errors and Messages

IntroductionThis appendix discusses errors and messages you may see in PAC Control and their possible causes. Errors and messages may appear with text only or with a negative number and text. The more common errors and messages are listed in this chapter in numeric order, starting on page 382.

To look up an error in PAC Control, select Help > Error Lookup. In the Error Lookup dialog box, enter the error code, and then click Get Error.

See also, “A: Troubleshooting” on page 367 for additional help in resolving errors.

Types of ErrorsAs you work in PAC Control, you may see three types of errors:

• PAC Control Errors appear in dialog boxes on the computer screen.

• Queue Messages (both errors and other messages) appear in the control engine’s message queue.

• Status Codes appear in variables or as returned values in OptoScript.

TYPES OF ERRORS


PAC Control ErrorsPAC Control errors indicate a problem within PAC Control that may have been reported by the control engine or may have occurred before control engine communication.

PAC Control errors appear in dialog boxes on the computer running PAC Control. Some of these errors appear as numbers, some as text, and some show both numbers and text. An example of a PAC Control error is “Timeout. No response from device.” Another example is “TCP/IP: Cannot connect error” with an error code of -412.

Queue MessagesQueue messages indicate an error or other message during strategy operation, and they appear in the PAC Control message queue. (For information on viewing the queue, see “Viewing the Message Queue” on page 111.) Here’s an example of a message queue:

This queue shows several types of messages that you might see. To see all the information in a column, drag the edge of the column heading to the right.

Code. Queue errors generated by the system are shown as negative numbers in the Code column. For example, if you specify a table index that is greater than the number of elements in the table, an error -12, “Invalid table index,” appears, as in message #3 above. Common queue errors for each command are listed in the PAC Control Command Reference and in online help.

If the Code column indicates User, the error is one you have placed in the queue using the command Add Message to Queue. User messages can help with troubleshooting. Message #2 above is an example of a message the user placed in the Temperature_Control chart.

Severity. The Severity column indicates the type of message: information, warning, or error.

Chart, Block, Line, Object. If a PAC Control command in the strategy caused an error, the chart name, block number, and line number (if you are in Full Debug mode) where the command appears are listed. Message #3 above is an example: an invalid table index was used in block 19 of the Temperature_Control chart. The Object column shows the table name.

APPENDIX B: ERRORS AND MESSAGES


If an error did not occur in a strategy chart, the Chart column shows <system>. Messages 1 and 2 occurred when the strategy was unable to initialize an I/O unit, so the Chart column shows <system: _INIT_IO>. Block and Line do not apply, but the Object column shows the name and IP address of the I/O unit.

If an error was caused by a subroutine, the Chart column shows the name of the chart that calls the subroutine, and the Block column shows the name of the subroutine and the block number where the error occurred, in the format <subroutine name>.<block number>. Messages 4, 5, and 6 are examples; these errors occurred in block 1 of the subroutine Variable_Increase_Notification, which was called by the Temperature_Control chart.

Using Queue Messages

If a block number is listed for the error, look in that block in the strategy to find the PAC Control command that caused the error. The easiest way to find a block is to open the chart or subroutine, then choose Center on Block from the View menu. You can click the Block column to sort the blocks by number and locate the one with the problem.

To see which line within a block is causing the error, in PAC Control Configure mode, choose Configure > Full Debug. When the error appears in the queue, it will include the line number of the command as well as the block ID.

Status CodesStatus Codes indicate the success or failure of a PAC Control command (instruction), and they are reported by the control engine to a variable in your PAC Control strategy or as a returned value in OptoScript. The status code is either zero (indicating a successful command) or a negative number (indicating an error).

For example, suppose you use the command Transmit Numeric Table. You create a variable named Transmit_Status to put the status of the command in. In Transmit_Status you receive either a zero, indicating that the table was successfully transmitted, or you receive a negative number such as -37 or -42.

Status codes that may be returned are listed for each command in the PAC Control Command Reference and in online help.

Naming ConflictsDuring various procedures, PAC Control checks for duplicate names of objects such as variables, charts, subroutines, strategy variables, OptoScript instruction names, and reserved keywords. If a naming conflict is found, you may need to rename an object or perform some other housekeeping procedures. When converting to a newer PAC Project, make sure to update PAC Control strategies first and then PAC Display projects so that PAC Display projects are updated based on changes to the strategy database.

LIST OF COMMON MESSAGES


List of Common MessagesThe following messages may appear in PAC Control. They are listed in numeric order.

If an X appears in the Q? column, the code number appears in the message queue. If an X appears in the I/O? column, the message is an I/O unit error and may appear either in the message queue, as a status code in a variable, or both. For more information on handling I/O unit errors, see “Error Handling Commands” on page 288 and form 1776, Optimizing PAC Project System Performance.

# Description Possible Cause Q? I/O?

0 Operation performed successfully. NOT AN ERROR. Indicates the command was successful.

-1 Undefined command. An unknown command was sent to the PAC Control engine.

-2 Checksum or CRC mismatch.When comparing DVFs (Data Verification Fields), a mis-match occurred. Examples of DVFs include checksum and CRC.

-3 Buffer overrun or invalid length error.In string manipulations, a string was requested that is longer than the string it will be put into, or the destination string length <= 0.

X X

-4 Device has powered up. ('Powerup clear expected' message received.)

NOT AN ERROR. The device has been turned off and then on again since the last communication, and is now ready. X

-5 Operation failed.An attempt to store the strategy to flash failed, or an attempt to do something with a chart failed (like call, continue, sus-pend, start, initialize threads).

-6 Data field error.Invalid year entered (must be between 2000 and 2099), or invalid data read from memory when attempting to read the strategy from flash memory.

X

-7 Watchdog timeout has occurred. See “Add I/O Unit Dialog Box” on page 123.

-8 Invalid data.Invalid data read when attempting to read a strategy from flash, or an invalid character number was passed to a string function.

-10 Invalid port number. Valid range for Ethernet is 0–65535. For a communication handle, serial port format may be incorrect. X

-11 Could not send data.A Transmit or Transfer command fails when using a comm handle. For example, an attempt is made to send a file to a remote ftp server that has gone off-line.

-12 Invalid table index. Used an index greater than the number of elements in the table. X X



-13 Overflow error.

Typically, a math result too big to fit in the value passed, while doing number conversion functions such as con-verting a float value to engineering units, a float to an unsigned integer, a float to an integer, a 64-bit integer to a 32-bit integer, a floating point value to a 64-bit integer, a floating point value to an unsigned 64-bit integer, an ASCII value to a float.

NOTE: In OptoScript, an If Statement expects an 32-bit number and will automatically convert any other type (such as 64-bit integer or float value) to a 32-bit number. To avoid this overflow error, a slight change to the code can avoid this problem. For example:

if (your_int_64_here) then...becomes:if (your_int_64_here <> 0) then...

Also math functions such as multiply, exponentiation, hyperbolic sine, hyperbolic cosine, function x to the y, add, subtract, modulo, negate, move/assign.

Time/date functions: setting a month not in the range 1–12, a day not in the range 1–31, hours not in 0–23, min-utes 0–59, seconds 0–59.

Number entered on host port (for example, through PAC Terminal) was too big for data types.

X

-14 Invalid number.

Math resulted in an invalid number (like infinity or an imagi-nary number): natural log of the floating point number, square root, arc sine, arc cosine of float, function x to the y (with negative x).

X

-15 Cannot divide by zero. Attempted to divide a number by zero. X

-16 Bus error. Contact Product Support. See page 5.

-17 Port already locked on PAC Control engine. Attempted to lock a connection that’s already locked. X

-20 Device busy. May be in use by another user or another application. A resource is already acquired by another task or process. X

-21 Had to relock host port in 'QUIT'. Host port needed relocking.

-23 Destination string too short.In string manipulations, a string was requested that is longer than the string it will be put into, or destination string length <= 0.

X X

-25 Port not locked. Attempted to transmit or receive on a connection that wasn’t locked, or to unlock a connection that wasn’t locked. X

-26 Unknown response from device. OptoMMP-based protocol packet returned by the device was invalid. X

-29Wrong object type. Most likely caused by moving a pointer table element to a pointer of the wrong type.

An object was passed to a command that doesn’t handle that object type.

-34 Invalid I/O command or invalid memory loca-tion. Contact Product Support. See page 5. X




-35 I/O Point mismatch

A point is incorrectly configured (for example, an output point is configured as an input point), or the point type is not supported by the I/O Unit's firmware. Check www.opto22.com for firmware updates.

X X

-36 Invalid command or feature not imple-mented.

Feature not yet implemented for this hardware/command combination, or command may not apply to the type of com-munication handle you are using.

X

-37 Timeout on lock. Unable to lock a resource (such as a variable) for exclusive writing within the timeout period. X

-38 Timeout on send. Unable to send communication in the timeout period.

-39 Timeout on receive. Unable to receive communication in the timeout period.

-42 Invalid limit (on string index, task state, prior-ity, etc.).

A character number greater than the length of the string was used (or the string had a zero length), or an invalid value was passed when setting the state of a chart (running, etc.)

-44 String too short.String less than 8 characters used to read time (“hh:mm:ss”), or not 8 or 10 characters for a date, or zero length on a string function.

X

-45 Null string. Attempted to use an uninitialized string.

-46 Invalid string.String not 8 characters long when setting time, or invalid for-mat when setting date, or invalid communication handle string or comm handle command (such as a missing colon).

X

-47 Invalid connection. Device drivers might be missing or not loaded/running. Attempted to open an already open connection. X

-49 No more connections are available. Maxi-mum number of connections already in use. No more sessions available for Ethernet. X

-50 Open connection timeout. Could not estab-lish connection within the timeout period. Unable to open a connection in time. X

-52 Invalid connection—not opened.Attempted to close a connection that wasn’t opened. Com-munication handle may have been closed by a previous command that failed.

X

-57 String not found. Substring not found in the string being searched.

-58No data received.orCharacter not found.

Attempted to read an empty buffer (or a connection with no characters waiting); or the I/O unit may be turned off or unreachable; or when searching a string for a particular character, the character wasn’t found.

X

-59 Could not receive data.

Command may not apply to the type of communication han-dle you are using; for example, Receive commands cannot be used with ftp comm handles. (Use the get option with Send Communication Handle Command instead.)

-60

Empty stack error. PAC Control engine attempted to perform an operation that expected data on the PAC Control engine stack.

Contact Product Support. See page 5.

-61

Dictionary full error. PAC Control engine dic-tionary is full and no more 'words' can be defined. Clear PAC Display words using PAC Display or PAC Terminal, if appropriate.

Attempted to create a variable, command, or similar item when there’s no room left. Or large string or numeric tables are being created in the strategy.




-62 Stack full error. PAC Control engine stack has grown too big. The PAC Control engine stack is full.

-64Execute-only error. A command or 'word' was encountered that cannot be used when compiling.

Contact Product Support. See page 5.

-66 Requested item in protected dictionary Attempted to remove a strategy when there was no strategy in the control engine.

-67

Out of memory. To minimize the size of your strategy, reduce the number and size of vari-ables (especially tables). You can also shrink your strategy by using subroutines to per-form common tasks

No room left to create any variables or save any data on the stack. Or an attempt was made to save the strategy to flash, without enough room in flash to save it.

X

-69 Invalid parameter (null pointer) passed to command.

Attempted to use an uninitialized pointer, or a null pointer was received by a command. X

-70 Not enough data supplied. Table index given is larger than the size of the table. X

-71 Out of persistent memory. If applicable, check length of tables.

Too many persistent variables, variables initialized on down-load, or too large a strategy archive to fit in battery-backed RAM.

-93

Communication to I/O unit not enabled. Pre-vious communication failure may have dis-abled communication to the unit automatically. Re-enable it and try again.

Communication to the I/O unit may have been disabled by a communication failure that happened earlier. X

-103Port could not be unlocked. Task attempting to unlock the port does not match the task with the current lock on that port.

Attempted to unlock a connection that was locked by a dif-ferent task. X

-203 Driver could not be found or loaded.Communication command didn’t find the driver described in the communication handle. Make sure driver name is not misspelled (for example, tcp must be lower case).

X

-407 File not found. Attempted to save a strategy to flash, but there was no strat-egy in RAM to save.

-412 TCP/IP: Cannot connect error Ethernet “connect” failed. See page 372. X

-417 Cannot open file File does not exist or filename may be incorrect.

-430 Invalid data range. Verify high value is greater than low value.

Invalid data passed to driver (for example, a point number larger than the maximum number of points on the rack). X

-433 Object/device already locked. Couldn’t set the state of a chart (running, suspended, etc.) because it’s already locked by something else.

-437 No acceptable socket interface found. Ethernet “accept” attempted, but no more sessions are available (32 total). X




-438 Could not create socket.

This error is generated when the controller has run out of available TCP sockets (a limited resource). This is most likely caused when the strategy is overaggressive when try-ing to establish TCP communications to other devices. When sockets are opened and fail or are closed, there is a time period that must expire before the socket resource may be reused. Sockets that are rapidly opened and closed will cause all available socket resources to enter this time period. When this occurs, any attempt to open an outgoing communication will fail with this error code because there are no available sockets to use for this attempt.

When an error occurs when trying to open a TCP communi-cation handle, the strategy should back off for a significant amount of time before reattempting. Subsequent failures should have additional delays applied. These delays slow the consumption of TCP resources.

X

-440 Could not bind socket.

Another device, such as the I/O on the brain, is already using the port. If you are using the Modbus toolkit, make sure to use PAC Manager to set the brain’s Modbus port to a number other than 502. Try 0.

-442 Could not accept on socket. Ethernet “accept” failed. X

-443 Could not receive on socket. Ethernet “receive” failed. X

-444 Could not send on socket. Ethernet “send” failed. X

-531 Buffer full.

Attempted to write to a full buffer. For a serial communica-tion handle, data is being sent faster than the serial port can send and buffer it. Use a faster baud rate or a delay between Transfer/Transmit commands.

X

-534 Attempts to communicate with I/O unit failed. I/O unit may have lost power or network connection. X X

-539 I/O error; performing retryI/O unit may have lost power or network connection. When communicating with I/O Units, retries are logged in the mes-sage queue.

X X

-700PID Loop has been configured outside of this strategy and could conflict with this strat-egy’s logic.

You are trying to download a new strategy, but a PID loop is currently running on the brain. Open PAC Manager and turn off the loop in Inspect mode by changing its algorithm to None.

-8607 Invalid protocol. Attempted to set a port to an unknown mode. X

-8608 Port initialization failed. While starting up a chart or task, the default host port could not be created. X




-8612 Old response to new command

Each command sent by the PAC controller has a sequence ID. Each response from an I/O unit includes the sequence ID of the command it is responding to. This allows the con-troller to verify that a response from an I/O unit matches the most recent command sent to that I/O unit. An out-of-sync error would occur (and be posted in the PAC controller's message queue) if the response received by the controller is for a previous command rather than the current command. It usually occurs like this:Controller sends a command and waits the timeout period for the response. If no response is received, it sends a re-transmit of the same command, but with a new sequence ID. The controller receives a response to the original com-mand, so the sequence ID does not match the current sequence ID. Possible problems:• Network problems. Out-of-sync errors typically occur when communication to the I/O unit is via a network with high latency or inconsistent latency, such as wireless Ether-net, radio modem, cell modem, etc. This usually does not occur on a wired network because normal response times are much shorter than the default timeout period for I/O Units (typically 1 Sec). Note: If an Ethernet packet from a controller to an I/O unit gets dropped, you would get a -539 error instead of an out-of-sync error. • The timeout interval is too short. Increase the timeout value to reduce out-of-sync errors.

X

All -10,000 and -11,000

errors[Various descriptions] Socket or network problems. Check cables and connections

to control engine; cycle power to control engine.



C: C: PAC Control FilesAppendix C

C: PAC Control Files

IntroductionThis appendix lists all of the PAC Control file types and special files. You can use this information to determine what types of files are present in your PAC Control project directory.

FILES RELATED TO A STRATEGY


Files Related to a Strategy

Files Associated with a Subroutine

<strategy>.idb PAC Control strategy database

<strategy>.crf Controller Run File (compiled file that is sent to the control engine)

<strategy>.crn Intermediate run file (compiled file that is sent to the control engine)

<strategy>.crn1 Intermediate run file (component of the run file)



<strategy>.inc Initialization data for variables with “Init on Download” option (component of the run file)

<strategy>.inf Strategy configuration information

<strategy>.$idb Temporary PAC Control strategy database file

<strategy>.lidb PAC Control strategy database lock file

<strategy>.per Persistent variable definitions

<strategy>.<control engine>.cdf Control engine download file for special circumstances (see page 181)

<chart name>.cht Chart

<chart name>.ccd Compiled chart code (component of the run file)

<chart name>.con Online compiled chart code

<chart name>.cxf Exported chart file

<filename>.wth Watch window file (you name the file)

<filename>.otg Exported I/O configuration file (you name the file)

<strategy.date.time>.zip Strategy archive file (automatically named; see “Archiving Strategies” on page 174 for file name formats)

<subroutine name>.isb Subroutine

<subroutine name>.ini Subroutine configuration information

<subroutine name>.isc Compiled subroutine (component of the run file)

<subroutine name>.lisb Subroutine lock file

APPENDIX C: PAC CONTROL FILES


Files in the PAC Control Directory<xxx>.io.def Object definition files (commands, I/O points, and I/O units).

You must not modify these files.

ioCtrl.exe PAC Control executable file

PAC Control.cnt PAC Control help contents file

PAC Control.GID PAC Control help support file (created when you launch the help file)

PAC Control.hlp PAC Control help file

PAC ControlCommands.cnt Commands help contents file

PAC ControlCommands.GID Commands help support file (created when you launch the help file)

PAC ControlCommands.hlp Commands help file

ioCtrlTools.dat File that lists software applications you’ve configured in the Tools menu to launch from PAC Control

ioSnif.log PAC Message Viewer log file

OptoScriptTemp.txt A temporary file

Readme.txt README text file containing information about PAC Control

FILES IN THE PAC CONTROL DIRECTORY



D: D: Sample StrategyAppendix D

D: Sample Strategy

IntroductionChapter 2 introduced the Cookies strategy, a sample project used to illustrate how PAC Control works. Although this strategy is based on a mythical factory, you may want to know more about the factory, its process, and its hardware. This appendix gives you that information.

Factory SchematicThe following schematic drawing summarizes the cookie factory:

DESCRIPTION OF THE PROCESS


Description of the Process

Dough VesselThe first station in our process is the dough vessel. This tank contains a pre-made cookie dough mix.

Dough is dispensed onto the conveyor belt through a valve (SV-100B) at the bottom of the vessel. The dough, being somewhat viscous, must be kept under low pressure to dispense properly. To monitor the pressure, we have included a pressure transmitter (PT-100) in the vessel. Our control engine (a SNAP PAC R-series I/O system) maintains the vessel pressure through a plant air valve (SV-100A).

The vessel also includes a level switch (LAL-100) to tell us when the dough level is low. When it is, the process is halted so that an operator can refill the vessel.

Chip HopperThe chip hopper supplies chocolate chips. A chip dispenser valve (SV-101) controls the number of chips dropped on each cookie. Like the dough vessel, this tank also includes a level switch (LAL-101) to stop the system when the chip hopper needs refilling.

OvenAfter the dough and chips have been dropped onto the conveyor, the conveyor sends the cookie into the oven, and the oven bakes it.

Inspection StationOur freshly baked cookies then move to the inspection station, where someone inspects them. If the cookie does not fall within normal tolerances— for example, it doesn’t have enough chips or is shaped oddly—the inspector closes a switch (XS-103), signalling the bad cookie. A valve (SV-103) then opens to allow plant air to blow the reject cookie into a waste bin.

If the cookie passes the inspection, it moves on to packaging and shipping.

ConveyorThe conveyor and its motor continuously move the cookies from the dough vessel to the inspection station. The conveyor speed is controlled through an analog output (SY-104) from a speed controller (SC-104).

APPENDIX D: SAMPLE STRATEGY


Emergency StopsWired at key locations around our bakery are emergency-stop buttons. If something goes wrong with the process, an operator can press any of these E-STOP buttons.

The buttons are wired in series and are normally closed, so pressing any E-STOP button breaks the circuit. One digital input can monitor all the buttons. The system can be restarted by resetting the button.

Required I/OHere’s the list of analog and digital I/O modules required for the cookie factory:

Analog I/O

Digital I/O

Name Description Type Module Range

PT-100 Dough Vessel Pressure Input SNAP-AIV (–10 to +10 VDC) 0–15 psig

TT-102 Oven Temperature Input SNAP-AICTD (ICTD) -50–350°C

TY-102 Oven Temperature Control Output SNAP-AOV-27 (–10 to +10 VDC) 0–100%

SY-104 Conveyor Speed Control Output SNAP-AOV-27 (–10 to +10 VDC) 0–100%

Name Description Type Module States

SV-100A Pressure Control Valve Output SNAP-ODC5SRC (5–60 VDC) 0=Closed1=Open

SV-100B Dough Dispense Valve Output SNAP-ODC5SRC (5–60 VDC) 0=Closed1=Open

LAL-100 Dough Level Alarm Input SNAP-IDC5D (2.5–28 VDC) 0=OK1=Low

SV-101 Chip Dispense Valve Output SNAP-ODC5SRC (5–60 VDC) 0=Closed1=Open

LAL-101 Chip Level Alarm Input SNAP-IDC5D (2.5–28 VDC) 0=OK1=Low

XS-103 Inspection Signal Input SNAP-IDC5D (2.5–28 VDC) 0=OK1=Reject

SV-103 Reject Valve Output SNAP-ODC5SRC (5–60 VDC) 0=Closed1=Open

XS-105 Emergency Stop Input SNAP-IDC5D (2.5–28 VDC) 0=Stop1=OK

REQUIRED I/O



E: E: OptoScript Language ReferenceAppendix E

E: OptoScript Language Reference

IntroductionThis appendix includes the following reference information about the OptoScript language:

OptoScript Comparison with Standard Programming Languages . . . . . . 397Notes to Experienced Programmers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 402OptoScript Lexical Reference. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 404OptoScript Grammar Syntax Reference . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 407

OptoScript Comparison with Standard Programming Languages

The tables on the following pages compare OptoScript functions and variables to those available in Pascal, BASIC, and C. For more information on using OptoScript, see “11: Using OptoScript,” on page 321.

General Notes:1. The BASIC column is based on Microsoft's Visual Basic language.2. The Pascal column is based on Borland's ObjectPascal language.3. The use of logical statements in BASIC and Pascal is significantly different than in

OptoScript and C. BASIC and Pascal have a Boolean data type; OptoScript and C use integers. OptoScript and C treat a zero value as false and a non-zero value as true.

4. In OptoScript, you cannot use a break type of command in a loop.

OptoScript can test only one case in a switch at a time; other languages can test more than one.

OPTOSCRIPT COMPARISON WITH STANDARD PROGRAMMING LANGUAGES


Func

tion

Com

pari

son

Opt

oScr

ipt

BA

SIC

1C

Pasc

al2

inte

ger 3

2 (d

ecim

al)

123

123

123

123

inte

ger 3

2 (h

exad

ecim

al)

0x12

3AB

C&

H12

3AB

C0x

123A

BC

&12

3AB

C

inte

ger 6

4 (d

ecim

al)

123i

64N

ot a

vaila

ble

123L

L or

123

i64

123

inte

ger 6

4 (h

exad

ecim

al)

0x12

3AB

Ci6

4N

ot a

vaila

ble

0x12

3AB

CLL

or 0

x123

ABC

i64

&12

3AB

C

float

(sta

ndar

d)12

.34

12.3

412

.34

12.3

4

float

(sci

entif

ic)

12.3

4E+1

71.

234E

+18

1.23

4E+1

712

.34E

+17

strin

g"h

ello

""h

ello

""h

ello

"'h

ello

'

char

acte

r65 'A

'N

ot a

vaila

ble

65 'A'

'A'

bloc

k co

mm

ent

/*

*/N

ot a

vaila

ble

/*

*/{

}

line

com

men

t//

'//

//

num

eric

ass

ignm

ent

n =

3;n

= 3

n =

3;n

:= 3

;

num

eric

tabl

e as

sign

men

tt[0

] = 1

;t[i

] = 2

;t[i

+1] =

3;

t(0) =

1t(i

) = 2

t(i +

1) =

3

t[0] =

1;

t[i] =

2;

t[i+1

] = 3

;

t[0] :

= 1;

t[i] :

= 2;

t[i +

1] :

= 3;

num

eric

exp

ress

ions

i = (f

* 2

.0) +

t[3]

;t[4

] = n

+ ((

x –

y) *

z);

i = (f

* 2

.0) +

t(3)

t(4) =

n +

((x

– y)

* z

)i =

(f *

2.0

) + t[

3];

t[4] =

n +

((x

– y)

* z

);i :

= (f

* 2.

0) +

t[3]

;t[4

] :=

n +

((x

– y)

* z

);

strin

g as

sign

men

ts

= "h

ello

";s

= s2

;s

= "h

ello

"s

= s2

strc

py(s

, "he

llo")

;st

rcpy

(s, s

2);

s :=

'hel

lo';

s :=

s2;

strin

g ta

ble

assi

gnm

ent

st[0

] = s

;st

[1] =

"hel

lo";

st[1

+i] =

st[5

];

st(0

) = s

st(1

) = "h

ello

"st

(1 +

i) =

st(5

)

strc

py(s

t[0],

s);

strc

py(s

t[1],"

hello

");

strc

py(s

t[1+i

], st

[5]);

st[0

] :=

s;st

[1] :

= 'h

ello

';st

[1+i

] :=

st[5

];

strin

g ch

arac

ters

n =

s[0]

;s[

0] =

'A';

Not

ava

ilabl

en

= s[

0];

s[0]

= 'A

';s[

0] :=

'A';

APPENDIX E: OPTOSCRIPT LANGUAGE REFERENCE


strin

g ex

pres

sion

s

s =

"hel

lo" +

s2

+ s3

;

s =

"hel

lo" +

Chr

(n);

s =

"hel

lo" +

s2

+ s3

;

s =

"hel

lo" +

Chr

(n)

strc

py(s

, "he

llo")

; st

rcat

(s, s

2);

sprin

tf(s,

"hel

lo%

c", n

);

s :=

'hel

lo' +

s2

+ s3

;

s :=

'hel

lo' +

Chr

(n);

equa

lx

== y

x =

yx

== y

x =

y

not e

qual

x <>

yx

<> y

x !=

yx

<> y

less

than

x <

yx

< y

x <

yx

< y

less

than

or e

qual

x <=

yx

<= y

x <=

yx

<= y

grea

ter t

han

x >

yx

> y

x >

yx

> y

grea

ter t

han

or e

qual

x >=

yx

<= y

x

>= y

x <=

y

logi

cal O

R (S

ee N

ote

3)x

or y

(x <

> 0)

Or (

y <>

0)

a O

r b (

bool

eans

onl

y)x

|| y

(x <

> 0)

Or (

y <>

0)

a O

r b (

bool

eans

onl

y)

logi

cal A

ND

x an

d y

(x <

> 0)

And

(y <

> 0)

x A

nd y

(bo

olea

ns o

nly)

x &

& y

(x <

> 0)

And

(y <

> 0)

a A

nd b

(bo

olea

ns o

nly)

logi

cal X

OR

x xo

r y(x

<>

0) X

or (y

<>

0)x

Xor

y (

bool

eans

onl

y)N

ot a

vaila

ble

(x <

> 0)

Xor

(y <

> 0)

a X

or b

(bo

olea

ns o

nly)

logi

cal N

OT

not x

Not

(x <

> 0)

Not

b (b

oole

ans

only

)!x

Not

(x <

> 0)

Not

b (b

oole

ans

only

)

logi

cal e

xpre

ssio

ns(x

>=

0) a

nd (y

==

3)no

t ((x

>0)o

r(no

t y==

3))

(x >

= 0)

And

(y =

3)

Not

((x

> 0)

Or (

y <

> 3)

)(x

>=

0) &

& (y

==

3)!((

x >

0) ||

(y !=

3)

(x >

= 0)

and

(y =

3)

not((

x >

0) o

r ( y

<>

3))

bitw

ise

NO

T bi

tnot

xN

ot x

~xno

t x

bitw

ise

OR

(See

Not

e 3)

x bi

tor y

x O

r yx

| yx

or y

bitw

ise

AN

Dx

bita

nd y

x A

nd y

x &

yx

and

y

bitw

ise

XO

Rx

bitx

or y

x X

or y

x ^

yx

xor y

bitw

ise

shift

left

x <<

yN

ot a

vaila

ble

x <<

yx

shl y

bitw

ise

shift

righ

tx

>> y

Not

ava

ilabl

ex

>> y

x sh

r y

bitw

ise

expr

essi

ons

i = x

bita

nd 0

x000

0FFF

F;i =

x <

< (i

* 2)

;i =

x A

nd &

H00

00FF

FFN

ot a

vaila

ble

i = x

& 0

x000

0FFF

F;i =

x <

< (i

* 2)

;i :

= x

and

&00

00FF

FF;

i :=

x sh

l (i *

2);

Opt

oScr

ipt

BA

SIC

1C

Pasc

al2

OPTOSCRIPT COMPARISON WITH STANDARD PROGRAMMING LANGUAGES


if st

atem

ent

if (i

== 2

) the

n /

/ do

som

ethi

ngen

dif

If (i

== 2

) The

n /

/ do

som

ethi

ngEn

d If

if (i

== 2

){ /

/ do

som

ethi

ng}

if (i

= 2)

then

begi

n /

/ do

som

ethi

ngen

d

if/el

se s

tate

men

t

if (i

== 2

) the

n /

/ do

som

ethi

ngel

se /

/ do

som

ethi

ng e

lse

endi

f

If (i

== 2

) The

n /

/ do

som

ethi

ngEl

se /

/ do

som

ethi

ng e

lse

End

If

if (i

== 2

){ /

/ do

som

ethi

ng} el

se{ /

/ do

som

ethi

ng e

lse

}

if (i

= 2)

then

beg

in

// d

o so

met

hing

end

else

beg

in

// d

o so

met

hing

els

e e

nd

if/el

se if

sta

tem

ent

if (i

== 2

) the

n /

/ do

som

ethi

ngel

seif

(i >=

5) t

hen

// d

o so

met

hing

els

eel

se

// d

o so

met

hing

els

een

dif

If (i

= 2)

/

/ do

som

ethi

ngEl

seIf

(i >=

5) T

hen

// d

o so

met

hing

els

eEl

se

// d

o so

met

hing

els

eEn

d If

if (i

== 2

){ /

/ do

som

ethi

ng} el

se if

(i >

= 5)

{ // d

o so

met

hing

els

e} el

se

{ // d

o so

met

hing

els

e}

if (i

= 2)

beg

in

// d

o so

met

hing

end

else

if (i

>=

5) b

egin

//

do

som

ethi

ng e

lse

end

else

b

egin

//

do

som

ethi

ng e

lse

end

for

loop

(See

Not

e 4)

for i

= 0

to 5

ste

p 1

MyT

able

[i] =

i *

2;ne

xt

For i

= 0

To

5 St

ep 1

MyT

able

(i) =

i *

2N

ext

for (

i = 0

; i <

5 ;

i++)

{ MyT

able

[i] =

i *

2;}

for i

:= 0

to 5

do

begi

n M

yTab

le[i]

:= i

* 2;

end

whi

le lo

op (S

ee N

ote

4)

whi

le (i

< 5

) M

yTab

le[i]

= i

* 2;

i =

i +

1;w

end

Whi

le (i

< 5

) M

yTab

le(i)

= i

* 2

i =

i +

1W

end

whi

le (i

< 5

){ M

yTab

le[i]

= i

* 2;

i =

i +

1;}

whi

le (i

< 5

) do

begi

n M

yTab

le[i]

:= i

* 2;

i :=

i +

1;en

d

repe

at lo

op (S

ee N

ote

4)

repe

at M

yTab

le[i]

= i

* 2;

i =

i +

1;un

til (i

> 5

);

Do

MyT

able

(i) =

i *

2 i

= i

+ 1

Loop

Unt

il (i

> 5)

do { MyT

able

[i] =

i *

2; i

= i

+ 1;

} whi

le !(

i > 5

);

repe

at M

yTab

le[i]

:= i

* 2;

i =

i +

1;un

til (i

> 5

);

Opt

oScr

ipt

BA

SIC

1C

Pasc

al2



Not

es:

1.Ba

sed

on M

icro

soft'

s Visu

al B

asic

lang

uage

.2.

Base

d on

Bor

land

's O

bjec

tPas

cal l

angu

age.

3.Th

e us

e of

logi

cal s

tate

men

ts in

BAS

IC a

nd P

asca

l is s

igni

fican

tly d

iffer

ent t

han

in O

ptoS

crip

t and

C. B

ASIC

and

Pas

cal h

ave

a Bo

olea

n da

ta ty

pe; O

ptoS

crip

t and

C u

se in

tege

rs. O

ptoS

crip

t and

C tr

eat a

zero

val

ue a

s fal

se a

nd a

non

-zer

o va

lue

as tr

ue.

4.O

ptoS

crip

t can

not h

ave

a br

eak

type

of c

omm

and

in a

loop

as i

s com

mon

with

oth

er la

nuag

es.

5.O

ptoS

crip

t can

test

onl

y on

e ca

se a

t a ti

me.

case

(See

Not

e 5)

switc

h (i)

cas

e 1:

f

= 2.

0 *

x;

bre

ak c

ase

z:

f =

2.0

* y;

b

reak

def

ault:

f

= 2.

0 *

z;

bre

aken

dsw

itch

Sele

ct C

ase

(i) C

ase

1

f =

2.0

* x

Cas

e z

f

= 2.

0 *

y C

ase

Els

e

f =

2.0

* z;

End

Sel

ect

switc

h (i)

{ cas

e 1:

f

= 2.

0 *

x;

bre

ak;

//cas

e z:

NO

T A

LLO

WE

D IN

C

//

f = 2

.0 *

y;

//

brea

k; d

efau

lt:

f =

2.0

* z;

b

reak

;}

case

i of

1:

f

:= 2

.0 *

x;

2:

f

:= 2

.0 *

y;

els

e

f :=

2.0

* z

;en

d;

Opt

oScr

ipt

BA

SIC

1C

Pasc

al2

NOTES TO EXPERIENCED PROGRAMMERS


Variable Comparison

Notes to Experienced ProgrammersExperienced programmers, especially those who are new to PAC Control, may be interested in the following notes.

Variable Database and Other SurprisesPAC Control maintains a database of all declared variables—a notable difference from common procedural languages. Variables are not declared in the programming code, but in the PAC Control tag database. This is a basic concept of PAC Control and how it ties in with PAC Display, but may seem odd to experienced programmers using PAC Control for the first time. Also, all variables and objects are global. Local variables do not exist in PAC Control in the way they do in most procedural languages. Subroutines in PAC Control contain “local” variables, but those local variables apply throughout that subroutine.

Most languages allow you to return from a function before it ends, but OptoScript does not. The same effect can be achieved in other ways, however, such as introducing tests into the code. (Some people argue that this limitation produces better programming, because each function has only one exit point.)

PAC Control's Target AudienceBecause PAC Control is based on OptoControl, which was conceived as a simple programming tool for non-programmers, it is designed to be relatively foolproof. Even though OptoScript provides advanced functionality, this philosophy also influenced the design of OptoScript. OptoScript exists only inside OptoScript blocks, which can only exist inside a flowchart. Flowcharts are the basis of PAC Control.

Variable Name

PAC Control Type

BASIC Example C Example Pascal Example

n integer 32 Dim n as Long long n; n: Integer;

nn integer 64 Not available LONGLONG d; d: Int64;

f float Dim f as Single float f; f: Single;

s string Dim as String char s[128]; s: ShortString;

p pointer not available long * pn; pn: ^Integer;

nt integer 32 table Dim nt(10) as Long long i[10]; nt: array[0..9] of Integer;

ft float 32 table Dim ft(10) as Single float f[10]; ft: array[0..9] of Single

st string table Dim st(10) as String char s[10][128]; st: array[0..9] of ShortString;

pt pointer table not available void * pt[10]; pt: array[0..9] of ^Integer;



Even an experienced programmer may want to think twice before using OptoScript blocks extensively. Many programmers like PAC Control's simplicity not for themselves but for the field technicians and maintenance personnel who will use it in the field. While you could write an entire chart (or conceivably an entire strategy) in one block, doing so would eliminate most of the advantages of using PAC Control. Consider limiting your use of OptoScript to math operations, complex string manipulation, and other logic most suited to scripting, so you retain PAC Control’s advantages for non-programmers.

Language SyntaxIn the same way, OptoScript syntax is meant to be simple enough for a beginner to understand but also easy for an experienced programmer to learn quickly.

Some programmers may wonder why OptoScript is not modeled after just one existing language, such as BASIC or C. Instead, one can clearly see influences from Pascal, BASIC, and C. PAC Control's target audience is one reason; internal consistency with PAC Control commands and the capabilities and limitations of Opto 22 control engines are another.

Some aspects of OptoScript were designed to be consistent with PAC Control commands. For instance, the bitwise and operator was named bitand in OptoScript because there is a command in PAC Control named Bit AND.

OptoScript provides all the functionality of Opto 22 control engines but is subject to their limitations. For instance, OptoScript provides some convenient ways of working with strings, but only to a certain point.

For example, in an assignment statement, strings can be added together like this:strDate = strMonth + "/" + strDay + "/" + strYear;

It would certainly be nice to use the same kind of string addition in a procedure call:TransmitString(strMonth + "/" + strDay + "/" + strYear, nPort);

However, due to the current abilities of control engines, this type of string addition inside a function call is not possible.

OPTOSCRIPT LEXICAL REFERENCE


OptoScript Lexical Reference

Token Syntax LegendTokens are the smallest units that the OptoScript compiler processes.

bold character: (parenthesis): [brackets]: opt subscript:no subscript:0+ subscript: 1 subscript: 1+ subscript:

specific charactercontent is treated as a unitset of possible itemsitem is optionalitem is not allowed0 or more items may be chosenone item must be chosenone or more items must be chosen

*: letter:

digit: non-zero-digit hex-digit:

any characterany character a through z, upper or lower caseone of [0 1 2 3 4 5 6 7 8 9]one of [1 2 3 4 5 6 7 8 9]one of [0 1 2 3 4 5 6 7 8 9 A B C D E F a b c d e f]



Literals and Names

Token Name Token Syntax Comments

Int32Literal

0[xX]1hex-digit1+

Hexadecimal Integer 32-bitGood examples: 0x12AB, 0X12aB, 0x0Bad examples: x123ABC, 0123ABC

0non-zero-digit1

digit0+

Decimal Integer 32-bitGood examples: 0, 123, 7890Bad examples: 123ABC

'[*'no]1'Single CharacterGood examples:'A', '1', ' 'Bad examples: '''

Int64Literal

0[xX]1hex-digit1+i64

Hexadecimal Integer 64Good examples: 0x12ABi64, 0X12aBi64, 0x0i64Bad examples: x123ABCi64, 0123ABCi64

0i64digit1i64

non-zero-digit0+i64

Decimal Integer 64Good examples: 0i64, 123i64, 7890i64Bad examples: 123ABCi64

FloatLiteral

digit0+ . digit1+

([Ee]1 [+-]opt

digit1+)opt

Float LiteralGood examples: 1.0, 2.3, 1.2e6, 1.2e-6, .1, .2e6Bad examples: 1., 1.e7, 1e7

StringLiteral "[*"no]0+"String Literal. Confined to single line.Good examples: "abc def"Bad examples: "abc"def"

NumericVariableStringVariableChartVariableDigIoUnitVariableMixedIoUnitVariablePointerVariableNumericTableStringTablePointerTableCommunicationHandle

[letter]1 [letter

digit _ ]0+

A letter followed by mix of letters, digits, and underscores. The name must be found in the PAC Control database.

Good examples: MyInt, MyInt2, My_Int_3Bad examples: _MyInt, 0MyInt

CommandProcedureCommandProcedureNoArgsCommandFunctionCommandFunctionNoArgs

[letter]1 [letter

digit _ ]0+

A letter followed by mix of letters, digits, and underscores. The name must be a built-in command or subroutine.

Good examples: Sine, Sine2, Sine_3Bad examples: _Sine, 0Sine

OPTOSCRIPT LEXICAL REFERENCE


Keywords (Reserved Words)

OperatorsThe following table lists operators in order of highest to lowest precedence:

ifthenelseelseifendif

fortostepnext

switchendswitchcasebreakdefault

whiledowend

repeatuntil

Chr

null

Operator Name/Meaning Comments

- negation

not logical not

bitnot bitwise not

* multiplication

/ division

% modulo division

- subtraction

+ addition

+= string append assignment

<< bitwise left shift

>> bitwise right shift

== equality

<> non-equality

< less than

<= less than or equal to

> greater than

>= greater than or equal to

bitand bitwise and

bitor bitwise or

bitxor bitwise exclusive or

and logical and

or logical or

xor logical exclusive or

not logical not

( ) parentheses no precedence



CommentsOptoScript has two kinds of comments: single line and block.

Single line comments are indicated by two slashes, followed by any sequence of characters, until the end of the line.

Examples:

i = a + b; // this is a comment

i = a + b; //determine i by adding a and b together

// i = a + b; // This whole line is commented out

Block comments are indicated by a slash and an asterisk (/*), followed by any sequence of characters, and ending with an asterisk and a slash (*/). This type of comment may span multiple lines. Block comments may not be nested.

Examples:

i = a + b; /*determine i by adding a and b together*/

i = a + b; /* determine i by adding

a and b together */

/* i = a + b; // determine i by adding a and b together */

OptoScript Grammar Syntax Reference Tokens are in regular type. Keywords and operators are in bold type.Syntax Rules are in italic type.

Program> StatementList

StatementList > Statement> StatementList Statement

Statement

[ ] brackets no precedence

: colon no precedence

; semi-colon no precedence

, comma separator no precedence

= assignment no precedence

& address of no precedence

Operator Name/Meaning Comments

OPTOSCRIPT GRAMMAR SYNTAX REFERENCE


> AssignmentStatement > StrAssignmentStatement> PtrAssignmentStatement> ProcedureCommand > FunctionCommand ; > ConditionStatement > ForStatement > WhileStatement > RepeatStatement > SwitchStatement

ProcedureCommand> CommandProcedureNoArgs ( ) ; > CommandProcedure (ArgumentList ) ;

FunctionCommand> CommandFunctionNoArgs ( ) > CommandFunction (ArgumentList )

ArgumentList> NumericExp > ArgumentList , NumericExp > StrIdentifier > ArgumentList , StrIdentifier > ObjVarIdentifier > ArgumentList , ObjVarIdentifier

NumericExp> ( NumericExp ) > NumericExp > LogicalExp > LogicalUnaryExp > AdditiveExp > MultiplicativeExp> BitwiseExp > NumIdentifier > NumericLiteral > FunctionCommand

LogicalExp> NumericExp and NumericExp> NumericExp or NumericExp> NumericExp xor NumericExp> NumericExp == NumericExp> NumericExp <> NumericExp> NumericExp < NumericExp> NumericExp <= NumericExp> NumericExp > NumericExp



> NumericExp >= NumericExp> StrIdentifier == StrIdentifier > PointerVariable == null> null == PointerVariable> null == PointerTable [ NumericExp ]> PointerTable [ NumericExp ] == null

AdditiveExp> NumericExp + NumericExp> NumericExp - NumericExp

MultiplicativeExp> NumericExp * NumericExp> NumericExp / NumericExp> NumericExp % NumericExp

NotNumExp> ObjVarIdentifier> StrIdentifier

BitwiseExp> bitnot NumericExp> NumericExp bitand NumericExp> NumericExp bitor NumericExp> NumericExp bitxor NumericExp> NumericExp << NumericExp> NumericExp >> NumericExp

AssignmentStatement> NumericVariable = NumericExp ; > NumericTable [ NumericExp ] = NumericExp ;> StringVariable [ NumericExp ] = NumericExp ;

PtrAssignmentStatement> PointerVariable = PointableIdentifier ;> PointerVariable = PointerTable [ NumericExp ] ;> PointerTable [ NumericExp ] = PointableIdentifier ;

PointableIdentifier> null> & StringVariable> & NumVarIdentifier> & ObjVarIdentifier

StrAssignmentStatement> StringVariable = StrExp ;> StringTable [ NumericExp ] = StrExp ;> StringVariable += StrIdentifier ; > StringVariable += Chr ( NumericExp ) ;

StrExp



> StrAdditiveExp> StrIdentifier> Chr ( NumericExp )

StrAdditiveExp> StrExp + StrExp

StrIdentifier> StringVariable> StringLiteral? StringTable [ NumericExp ]

NumIdentifier> NumVarIdentifier> NumTableIdentifier> StringCharIdentifier

NumVarIdentifier> NumericVariable

ObjVarIdentifier> ChartVariable> DigIoUnitVariable> MixedIoUnitVariable> TableIdentifier> CommunicationHandle

NumTableIdentifier> NumericTable [ NumericExp ]

TableIdentifier> NumericTable> StringTable

StringCharIdentifier> StringVariable [ NumericExp ]

NumericLiteral> Integer32Literal> Integer64Literal> FloatLiteral

LogicalUnaryExp> not NumericExp

ConditionStatement> IfStatement

StatementListOrEmptyEndifStatement

> IfStatementStatementListOrEmpty

ElseStatement





ElseIfListEndifStatement


ElseIfListElseStatement


IfStatement> if ( NumericExp ) then

ElseStatement> else

ElseIfStatement > elseif ( NumericExp ) then

StatementListOrEmpty

ElseIfList> ElseIfStatement> ElseIfList ElseIfStatement

EndifStatement> endif

CaseList> CaseStatement> CaseStatement DefaultStatement> CaseList CaseStatement> CaseList CaseStatement DefaultStatement

DefaultStatement> default :

StatementListOrEmptybreak

CaseStatement> case NumericExp :

StatementListOrEmptybreak

SwitchStatement> switch ( NumericExp )

CaseListendswitch

ForStatement



> for NumericVariable = NumericExp to NumericExp step NumericExp StatementListOrEmpty

next

WhileStatement> while ( NumericExp )

StatementListOrEmpty wend

RepeatStatement> repeat

StatementListOrEmptyuntil NumericExp ;


Index

Aaction block

definition 213action command

definition 54active address 289adding

analog point 132command 247

in OptoScript 347communication handle 233digital point 128I/O unit 122numeric variable 233PID loop 142pointer 233pointer variable to watch window 244string variable 233table variable 237table variable to watch window 245, 247text to chart 220variable 233variable to watch window 242

algorithms for PID loops 303analog

adding I/O point 132changing I/O while strategy is running

151copying I/O point 138I/O unit commands 289minimum/maximum value 256, 257offset and gain commands (instructions)

256point commands 256, 331

point, definition 50TPO 256

applicationslaunching from PAC Control 70

archiving strategiesrestoring archives 116to computer 174to the control engine 115, 175

argument 80, 249in OptoScript 333

ASCII, decimal and hex values of characters317

auto stepping through a chart 187, 189automation 49autorun 184

Bbackground downloading 178, 179baud rate and mode for serial I/O units (Pro)

126baud rate for serial I/O units 125bill of materials 201bit commands 295bitwise operator, in OptoScript 341block

block 0 212changing color or size 214, 223connecting blocks 218definition 213deleting 223drawing 216finding in a chart 66moving 222naming 83, 217


OptoScript 322selecting 221stepping through 187

BOM 201bookmark 349breakpoints in a chart 190

Ccalling a subroutine 362case statement 328, 343

programming example 88changing

active control engine 108analog I/O while strategy is running 151baud rate and mode for serial I/O units

(Pro) 126baud rate for serial I/O units 125block color or size 214, 223chart background 214chart name or description 225column width in a dialog box 67command (instruction) 251connection line color or size 223control engine definition 108debug level 185debugger speed 186digital I/O while strategy is running 149I/O points 141I/O unit configuration 128I/O while strategy is running 148numeric variable 242PID loop 147pointer table 247pointer variable 244scale of a chart 64strategy download compression 183string table 245string variable 242text color or size 214, 223text in chart 220variable 241

chartadding text to 220auto stepping 187, 189breakpoints 190calling a subroutine 362

changing background 214changing name or description 225changing scale 64closing 224commands 258contents 213copying 225creating 211definition 53deleting 226designing 78exporting 227finding a block 66flow-through logic 81guidelines for design 81importing 228loop logic 81looping 327monitoring in watch window 165naming 82, 225opening 224pausing 187printing commands (instructions) 197printing graphics 194replacing elements 205saving 171, 224searching 203status 53, 193stepping through 187viewing 61, 193zooming in or out 64

chart elementchanging color or size 223cutting, copying, and pasting 222moving 222selecting 221

closingchart 224strategy 171, 173

commandadding 247adding in OptoScript 347arguments 80changing 251commenting out 252cutting, copying, and pasting 252, 253definition 54


deleting 251deleting temporarily 252for continue block 253groups

analog point commands 256chart commands 258communication commands 259control engine commands 282error handling commands 288I/O unit—event message commands

291I/O unit—scratch pad commands 293I/Ounit—memory map commands

292logical commands 295mathematical commands 297miscellaneous commands 301PID—Ethernet commands 302pointer commands 306simulation commands 308string commands 309time/date commands 318timing commands 319

in OptoScript 331function 334procedure 333

printing 197comment 252, 301

in OptoScript 349, 407communication

Ethernet link redundancy 102I/O memory map commands (instruc-

tions) 292I/O unit—event message commands (in-

structions) 291I/O unit—scratch pad commands 293incoming 263link redundancy 289outgoing 261PC and control engine 97peer-to-peer 261, 293TCP/IP 259, 261with serial communication module 261,

265, 267communication commands 259communication handle

adding 233

definition 54, 231, 259examples

File 271FTP 275serial 279TCP 265, 266

File 269FTP 275port numbers 262serial 278serial communication modules 265TCP 259, 261types 259viewing 242

comparison operators 339compiling

copy errors and warnings 176strategy 27, 175strategy without downloading 178subroutine 361

condition blockdefinition 213

condition command, definition 54condition in OptoScript 329configuration mode toolbar 58Configure mode, definition 57configuring

continue block 253control engine 97I/O points 128I/O unit 119PID loop 141, 303serial module 137subroutine parameters 357table variables 237variables 233

connection linechanging color or size 214, 223definition 213deleting 223drawing 218moving 222selecting 221

constant, See literalcontinue block

command (instruction) 253configuring 253


definition 213control characters, adding to string 311control concepts 49control engine

active control engine 108archiving strategies 115changing definition 108changing the active control engine 108commands (instructions) 282configuring 97definition 49deleting from strategy 109download file, creating 181inspecting 109removing association with strategy 109restoring archived strategies 116testing communication 370viewing message queue 111

control networksegmenting from company network 101

control structures, in OptoScript 342control system example 48controller, See control engineconverting a strategy 381converting IEEE float 298copying

block 222chart 225command (instruction) 252, 253configured I/O point 138connection line 222I/O configuration 121text block 222

count variable programming example 87counter

commands (instructions) 284programming example 86

CRC commands 282creating

flowchart 211PID loop 141strategy 169subroutine 355watch window 165See also changing

cross reference window 200cutting

block 222command (instruction) 252, 253connection line 222text block 222

Ddata

IEEE float format 298data format

IEEE float 298data types in subroutines 354data, sorting, in a dialog box 67date commands 318Debug mode

definition 57inspecting control engine 109inspecting I/O 148

debug mode toolbar 59debugging

changing speed 186choosing level 185strategy 185subroutines 364when using OptoScript 352

delaycommands 319

deletingchart 226chart elements 223command (instruction) 251command, temporarily 252control engine association with strategy

109control engine from strategy 109I/O point 141I/O unit 128PID loop 147variable 242

designingbasic rules for strategies 81steps for 73

dialog boxsizing columns 67sorting columns 67

digitaladding digital point 128


changing I/O while strategy is running149

copying I/O point 138counter 284I/O unit commands 289latches 284point commands 331point, definition 50pulse commands (instructions) 285quadrature counter 285totalizer 285

directory listing 277disabling I/O 286docking

Strategy Tree 63watch window 167

down timers 319downloading

files using FTP 275files using PAC Terminal 118initialization file for table variable 240strategy 175, 179

changing compression 183without using PAC Control 181

drawing toolbar 213duplicate object names 381

Eediting, See changingEEPROM, See flashelapsed time 192error

cannot delete item 368copy compile errors 176queue 111, 380status codes 381TCP/IP cannot connect 372types 380See also troubleshooting

error handlingcommands (instructions) 288programming example 86

error lookup 379Ethernet

connections 268link redundancy 102

commands for 289ports 268

Ethernet I/O units and commands 208example

case statements 88, 328complex operations 330control system 48counter 86creating messages to display on screen 84error handling chart 86File communication handle 271flag lock 90FTP communication handle 275if statements 329loops 327mathematical expressions 323pointers (indexing) 92repetitive actions 87serial communication handle 279string building 313, 325string data extraction 312string formats 311string table 312subroutine parameters 359TCP communication handle 265timer 89

exiting, See closingexporting

chart 227I/O configuration 121

FFile communication handle 269

examples 271file system on the brain

moving files via FTP 275saving files to flash 282

finding a block in a chart 66flag lock example 90flash memory 148

saving files to 282saving strategy to 173

floatIEEE 298

floating pointconverting to integer 300


converting to string 316definition 53in logic 296variable, definition 230

flowchart, See chartflow-through logic 81for loop 327, 345format

File communication handle 269FTP communication handle 275IEEE float 298serial communication handle 279TCP communication handle 261

FTPdirectory listing 277

FTP communication handle 275full debug, definition 185functions in OptoScript 331

Ggain

and offset 256in PID loops 159

grammar in OptoScript 407

Hhardware requirements for PAC Control 6help

See also troubleshootinghelp, online 72hex display mode 69high-density digital

enabling commands 208high-density points 290host task

definition 54Hungarian notation 83, 334

II/O

changing configured point 141configuring 128copying configured point 138deleting configured point 141

disabling 286exporting configuration 121importing configuration 122in strategy design 75, 77monitoring in watch window 165moving configured point 137naming points 83point numbers 122point, definition 49saving configuration 148segmenting I/O from host network 101using in OptoScript 331viewing all in a strategy 198, 200

I/O unitadding 122changing 128commands 289, 291, 292, 293configuring 119definition 119deleting 128exporting configuration 121importing configuration 122monitoring in watch window 165point numbers 122

IEEE float 298if statements

in OptoScript 343if/then statements 329importing

chart 228I/O configuration 122

info, viewing 111initialization file 118, 238

creating 239downloading 240

input pointdefinition 49disabling 286

input/output, See I/Oinspecting

control engine 109control engine using PAC Terminal 114I/O 148I/O using watch window 165PID loop 153See also viewing

installing PAC Control 5


instruction, See commandinteger

converting to float 300definition 53, 297in logic 296variable, definition 231

interacting algorithm for PID 303IO Enabler 288IP address

loopback 262, 266ISA algorithm for PID 303IVAL 286

Kkeyboard shortcuts 71

Llag time, for PID 154latch

commands (instructions) 284launching, See openinglegacy options, enabling 207link redundancy 289literal

constant 233in OptoScript 405

load last mode at startup 171load last strategy at startup 171local subroutine parameter 354local variable 354log file 391logic, in charts 81logical commands (instructions) 295logical operator in OptoScript 341logical true and false 296look up an error 379loop logic 81loopback address 262, 266looping 327, 344, 345

Mmathematical commands (instructions) 297mathematical expressions 323

in OptoScript 339

memory 369memory map commands 292message on screen, programming example

84message queue 111microSD card 270, 275minimal debug, definition 185minimum/maximum value 256, 257mistic I/O units and commands 209mode

Configure, definition of 57Debug, definition of 57Online, definition of 57

modifying, See changingmonitoring, See inspecting and viewingmoving

block 222connection line 222files via FTP 275I/O point 137text block 222to another window or chart 61

multitasking 54and strings 310

Nnaming

block 83, 217, 218chart 82, 225conventions 82, 83, 334I/O points 83variables 83, 334

naming conflicts 381network

segmenting control network 101network redundancy 102number, converting to string 316numeric literals in OptoScript 335numeric table

adding 237as alternative to strings 310

numeric variableadding 233in OptoScript 335


Ooffset and gain commands (instructions) 256offset, definition 256online help 72Online mode

avoiding memory problems 58definition 57

online mode toolbar 58opening

applications from PAC Control 70chart 224strategy 170watch window 166

operatorbitwise, in OptoScript 341comparison, in OptoScript 339in standard commands (AND/OR) 250logical, in OptoScript 341order of precedence 406

OptoScriptbitwise operators 341block example 322block, definition 213bookmark 349case statements 328, 343command types 333commands 331comments 407communication handle 273comparison operators 339comparison with other languages 397complex loops 327conditions 329control structures 342debugging strategies 352definition 321editor 346for loop 345functions 331if statements 343language reference 397literals 405logical operator 341math expressions 323, 339notes for programmers 402numeric literals 335numeric variables 335

pointers 337precedence for operators 406repeat loop 345string handling 325strings 335switch statements 343syntax 332, 403, 407tables 338toolbar 347troubleshooting 350types of commands 333when to use 322while loop 344

OptoVersion utility 375order of precedence for operators 406output point

definition 49disabling 286

PPAC Control

definition 47designing a strategy 73directory, list of files in 391errors 380files, list of 390installing 5main window 56mode 57opening other applications 70programming 73, 321system requirements 6

PAC Display 54PAC Manager 119PAC Message Viewer utility 373PAC Terminal utility

downloading files 118inspecting control engines 114testing communication with control en-

gine 370PAC Utilities 114, 118, 370, 373, 375page setup for printing graphics 195panning 65parallel algorithm for PID 303parameters, subroutine 353, 357passed-in subroutine parameters 354


pastingblock 222command (instruction) 252, 253connection line 222text block 222

pausingchart 187

peer-to-peer communication 261, 293permanent storage, See flash memorypermissions in Windows 376persistent data 233persistent RAM 369PID loop

algorithms 303changing 147configuring 141, 303definition 302deleting 147determining system lag 154inspecting 153tuning 159

PID—Ethernet commands 302pointer

adding 233commands 306, 337definition 54, 231, 306in OptoScript 337programming example (indexing) 92

pointer table 307adding 237

portEthernet 268peer-to-peer communication 262

Powerup chart 53uses 82

precedence for operators 406primary and secondary addresses

for I/O unit 124printing

bill of materials 201chart commands (instructions) 197chart graphics 194chart instructions 254page setup 195subroutine commands 197

problems, see troubleshootingProduct Support 5

programmingcomparing OptoScript with other lan-

guages 397examples 84in PAC Control 73

pulsecommands (instructions) 285

Qquadrature counter commands (instructions)

285queue

checking messages 111, 380quotation marks in strings 335

RRAM 369redundant communication links 102, 289redundant controllers 107repeat loop 327, 345repetitive actions programming example 87replacing elements 205resolution, timer 319retrieving a directory listing 277RTS/CTS 280running a strategy 29

automatically 184manually 184

Ssaving

chart 171, 224configurations to flash memory 148files to flash memory 282strategy 171strategy to flash 173subroutine 361

saving I/O unit configuration 148scratch pad commands 293searching 203secondary address 124segmenting control network 101selecting

block or text block 221


connection line 221serial communication handle 278serial communication module

communicating with 261, 265, 267configuring 137

serial devices, communicating with 278serial I/O unit

changing baud rate 125changing baud rate and mode (Pro) 126

setpoint, for PID 141setting hex display mode 69shortcuts, keyboard 71Simple I/O units and commands 208simulation commands 308sizing columns in a dialog box 67SNAP PAC redundancy option 107SNAP-PAC-S2

RTS/CTS 280software, launching from PAC Control 70sorting columns in a dialog box 67starting a strategy 184status codes 381step into 187step out 187step over 187stepping

inside blocks 188one block at a time 187through a chart 187within a block 185

stoppingstrategy 185

strategyarchiving

to computer 174to control engine 115, 175

closing 171, 173compiling 27, 175compiling without downloading 178creating 169debugging 185debugging when using OptoScript 352definition 55, 169deleting control engine 109designing 73, 81disassociating control engine 109downloading 175, 179

downloading, changing compression 183downloading, without using PAC Control

181files 390including subroutine 361opening 170replacing elements 205restoring archive from control engine 116running 29

automatically 184manually 184

saving 171saving to flash EEPROM 173searching 203stopping 185viewing all operands 200viewing variables and I/O 198

Strategy Treedefinition 60docking 63icons 60

stringadding control characters 311building, example of 313commands 309, 335

equivalents in Visual Basic and C 315convert-to-string commands 316data extraction, example of 312definition 53examples 311, 335in OptoScript 335length and width 310quotation marks 335variable, adding 233variable, definition of 231

string handling 325string table

adding 237example 312

subroutineadding commands (instructions) 360adding local variables 360auto stepping 189breakpoints 190calling from a chart 362compiling 361configuring parameters 357


configuring parameters, example 359creating 355data types 354debugging 364definition 353including in strategy 361list of files in 390parameters 353pausing 187printing commands 197printing graphics 194saving 361searching 203stepping through 187tips 355viewing 364viewing all operands 200viewing variables 198

Switch & Run 178switch statement 328, 343switching strategies 178, 179sync block

definition 213syntax

common errors, in OptoScript 351in OptoScript 332, 403, 407

system requirements for PAC Control 6

Ttable

commands 290, 301in OptoScript 338numeric table as alternative to strings 310

table variable 232adding 237changing 245, 247configuring 237initializing during strategy download 238monitoring in a watch window 245, 247

tabs, using to view windows 61target address 289task queue 258TCP communication handle 259, 261TCP/IP cannot connect error, resolving 372text block

deleting 223

moving 222selecting 221

text, changing color or size 214, 223time/date commands (instructions) 318timer

commands (instructions) 319definition 53down timer 319programming example 89resolution 319up timer 320variable, definition 231

timing a process, commands used for 318toolbar 58

drawing 213OptoScript 347

toolbarsconfiguration mode and online mode 58debug mode 59

totalizer commands (instructions) 285TPO 256trigonometry commands (instructions) 297troubleshooting

how to begin 367in OptoScript 350memory problems 369memory problems from Online mode

changes 58PAC Message Viewer utility 373Product Support 5Windows permissions 376

tuningPID loop 159

types of OptoScript commands 333

UUltimate I/O units and commands 208up timers 320

Vvariable

adding 233changing 241, 242, 244configuring 233definition 55, 229


deleting 242in strategy design 77literal (constant) 233monitoring in a watch window 165, 242,

244naming 83, 334OptoScript compared to other languages

402persisent data in 233pointer, definition 306table 232types of data 230types, in PAC Control 231viewing all in a strategy 198, 200

velocity algorithm for PID 303version, checking with OptoVersion 375subroutine

viewingviewing, See also inspectingviewing

all operands 200all variables and I/O 198another window or chart 61bill of materials 201chart 193chart instructions 254communication handle variable 242message queue 111numeric table variable 245numeric variable 242PID loop 153pointer table variable 247

pointer variable 244string table changing

numeric table 245string variable 242subroutine 364

Wwarning

copy compile warnings 176viewing 111

watch windowcreating 165docking 63, 167monitoring pointer variable 244monitoring table variable 245, 247monitoring variable 242opening 166

while loop 327, 344Windows

permissions 376

XXVAL 286

Zzooming in or out 64z-order, changing 222